467 lines
83 KiB
Plaintext
467 lines
83 KiB
Plaintext
Long Range Shooting
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Handbook
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Ryan M. Cleckner, Esq.
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Copyright © 2016 Cleckner, LLC All Rights Reserved.
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Published By:
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North Shadow Press, an imprint of Cleckner, LLC
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5543 Edmondson Pike
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Nashville, TN 37211
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To order additional copies of this book,
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products discussed herein, or to learn about
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additional books and projects, please visit
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the author’s website at
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www.RyanCleckner.com
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ISBN: 151865472X ISBN-13: 978-1518654725 Photography, Illustration, and Design by: Ryan M. Cleckner Edited by: William Keller and Iain Harrison
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DISCLAIMER: This publication contains content intended to educate readers about long range shooting principles and theories as well as assist readers in safely handling and shooting firearms. Readers are responsible for their own firearm safety. The publisher and author assume no liability for the careless handling of, or misuse of, firearms.
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Ryan is a firearms attorney who helps and represents FFLs all across the country. He’s also started a new project to help people get their own FFLs:
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RocketFFL is the premier resource for getting your Federal Firearm License (FFL), becoming an SOT (Class 2 or 3), and learn about firearm compliance. Learn more at https://www.RocketFFL.com
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Get Your Own FFL - Use our online guide to help you get your very own Federal Firearm License (FFL) and start buying and selling guns, or even make your own firearms, fast! Complete step-by-step guide makes it easy. Become an SOT - If you already have your FFL, becoming an SOT will allow you to start dealing in or making Silencers, Machine Guns, Short Barreled Rifles and Shotguns, and more! Learn About Firearms Compliance - Getting your FFL is just the first step – now you’ve got to comply with the MANY rules and regulations! Our online training courses make it easy!
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Courses available: Get Your FFL: http://courses.rocketffl.com/courses/get-your-ffl Become an SOT: http://courses.rocketffl.com/courses/become-an-sot-class-3 Compliance Training: http://courses.rocketffl.com/collections/compliance-courses
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DEDICATION
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I dedicate this book to the memory of the Ranger heroes who made the ultimate sacrifice during the Battle of Takur Ghar:
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SGT Bradley S. Crose SPC Marc A. Anderson CPL Matt A. Commons
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CHAPTERS
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1 Firearm Safety 2 How to Use this Book
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Equipment
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3 Ammunition 4 Rifles 5 Aiming Systems 6 Accessories 7 Selecting the Right Rifle, Scope, and Ammunition
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Fundamentals
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8 Fundamentals of Marksmanship 9 Units of Measurement 10 Ballistics 11 Environmental Effects
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Application
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12 Scope Mounting and Setup 13 Shooting 14 Spotting 15 Zeroing Your Rifle 16 Alternate Positions
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17 Estimating and Adjusting for Target Distance 18 Estimating and Adjusting for Wind 19 Estimating and Adjusting for Angles 20 Cleaning Your Rifle
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Appendix
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Ballistic Tables Log Book Targets About The Author
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TABLE OF CONTENTS
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1 Firearm Safety 1.1 Safe Firearm Handling 1.2 Safe Firearm Use
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2 How to Use this Book 2.1 Format 2.2 Website/Supplemental Information 2.3 Feedback 2.4 Sections 2.4.1 Equipment 2.4.2 Fundamentals 2.4.3 Application
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Equipment
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3 Ammunition 3.1 Bullets 3.1.1 Bullet Design Shape Weight Size 3.1.2 Parts of a Bullet Tip Ogive Shank / Body Base 3.1.3 Components of a Bullet Jacket
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Core 3.2 Powder
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3.2.1 Black Powder 3.2.2 Smokeless Powder
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Ball Powder Extruded Powder Flake Powder 3.3 Case 3.4 Primers 3.4.1 Types of Primers Berdan Boxer
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4 Rifles 4.1 Types of Rifles 4.1.1 Cycles of Function 4.1.2 Bolt-action Rifles 4.1.3 Semi-auto Rifles 4.1.4 Bolt vs. Semi 4.2 Common Parts 4.2.1 Receiver 4.2.2 Barrel Chamber Rifling Twist Rate Throat Contour Length 4.2.3 Trigger Single / Double-Stage Lock-Time 4.2.4 Hammer/Striker 4.2.5 Sear 4.2.6 Stock Bedding Style
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4.3 Add-ons 4.3.1 Bipod 4.3.2 Sling 4.3.3 Cheek Bag 4.3.4 Bubble Level
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5 Aiming Systems 5.1 Scopes 5.2 Scope Components/Features 5.2.1 Lenses Scope Caps 5.2.2 Reticle 5.2.3 Scope Body 5.2.4 Turrets Zero-Stops Bullet Drop Compensators 5.2.5 Target Focus/Parallax Adjustment Adjustable Objectives vs. Side-Focus Knobs Fixed Parallax 5.2.6 Magnification Adjustable Magnification Fixed-Power 5.3 Scope Adjustments 5.3.1 Elevation and Windage Adjustments Elevation Windage 5.3.2 Adjustable Magnification Second Focal Plane (SFP) First Focal Plane (FFP) 5.3.3 Adjustable Parallax / Target Focus 5.4 Scope Mounts 5.4.1 Rings 5.4.2 Base 5.5 Iron Sights 5.6 Adjusting Iron Sights 5.7 Laser Sights
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6 Accessories 6.1 Shooting Bag 6.2 Sand Sock 6.2.1 Sand Sock Use 6.3 DOPE Book 6.4 Calculators 6.4.1 Mechanical Calculators 6.4.2 Standard Electronic Calculators 6.4.3 Ballistic Calculators 6.5 Wind Meter 6.6 Chronograph 6.6.1 Optical Chronographs 6.6.2 Electromagnetic Chronographs 6.6.3 Doppler Radar 6.7 Tools 6.7.1 At-home 6.7.2 In Your Range Bag 6.8 Spotting Scope / Binoculars 6.8.1 Spotting Scope 6.8.2 Binoculars Setting up Binoculars 6.9 Laser Rangefinder
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7 Selecting the Right Rifle, Scope, and Ammunition 7.1 Bolt Action Rifles 7.1.1 Trigger 7.1.2 Stock 7.1.3 Barrel 7.2 Semi-auto Rifles 7.2.1 Trigger 7.2.2 Stock/Exterior Free-float Fore-end Buttstock 7.2.3 Barrel 7.3 Scopes 7.3.1 FFP/SFP
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7.3.2 Reticle 7.3.3 Turrets 7.4 Ammunition 7.4.1 Match-grade Ammo 7.4.2 Caliber Selection
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Fundamentals
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8 Fundamentals of Marksmanship 8.1 Aiming with Iron Sights 8.1.1 Sight Alignment 8.1.2 Sight Picture Center Hold 6 o’clock Hold Line of White/Sub-6 Hold 8.2 Aiming with a Scope 8.2.1 Sight Alignment 8.2.2 Sight Picture 8.2.3 Magnification 8.3 Aiming Generally 8.3.1 Focus on What you Can Control 8.3.2 Aim Small / Miss Small 8.3.3 Calling Your Shots 8.4 Trigger Control 8.4.1 Follow Through 8.4.2 Dry-Fire 8.5 Stable Position 8.5.1 Breathing/Pulse
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9 Units of Measurement 9.1 Linear Measurements 9.1.1 Yards (yds) 9.1.2 Meters (m) 9.1.3 Converting Between Yards and Meters 9.1.4 Linear Conversion Charts 9.2 Angular Measurements
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9.2.1 Minute of Angle (MOA) 9.2.2 Milliradian (Mil) 9.2.3 Using MOA and Mils 9.2.4 Converting Between MOA and Mils 9.2.5 MOA vs. Mil 9.3 Other Measurements 9.3.1 Mass / Weight 9.3.2 “Speed”
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Speed Velocity Acceleration 9.3.3 Energy 9.3.4 Bullet Efficiency G1 Drag Model G7 Drag Model
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10 Ballistics 10.1 Internal 10.1.1 Ignition Types of Powder Powder Quantity Resistance Volume 10.1.2 Projectile Acceleration Recoil 10.2 External 10.2.1 Gravity 10.2.2 Ballistic Line-of-Sight Ballistic Loophole 10.2.3 Calculating Bullet Path 10.2.4 Uphill/Downhill Effect 10.2.5 Bullet Efficiency 10.2.6 Supersonic / Subsonic Flight Trans-sonic Zone Magnus Effect 10.2.7 Spin Stabilization
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10.2.8 Spin Drift Poisson Effect
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10.2.9 Coriolis Effect Horizontal Component Vertical Component / Eotvos Effect
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10.2.10 Additive Shift 10.3 Terminal
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10.3.1 Energy. 10.3.2 Momentum
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11 Environmental Effects 11.1 Air Density 11.1.1 Air Pressure Station Pressure Barometric Pressure Effect on a Bullet 11.1.2 Temperature Ambient Temperature Ammunition Temperature 11.1.3 Humidity 11.1.4 Additive Effect
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Application
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12 Scope Mounting and Setup 12.1 Mounting the Base 12.1.1 Integral Bases 12.1.2 Ring and Base Combos 12.1.3 Bedding Your Base 12.1.3 Mounting Instructions 12.2 Mounting the Rings 12.2.1 One-piece Rings 12.2.2 Quick-Detach Rings 12.2.3 Vertically Split Rings 12.2.4 Mounting Instructions 12.3 Mounting the Scope
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12.3.1 Mounting Instructions 12.4 Adjusting the Scope
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12.4.1 Ocular Focus 12.4.1 Target Focus
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13 Shooting 13.1 Shooter Position 13.1.1 Body Shoulder Head 13.1.2 Natural Point of Aim 13.1.3 Shooting Hand 13.1.4 Support Hand 13.2 Rifle Position 13.2.1 Cant 13.3 Rifle Manipulation 13.3.1 Mounting the Rifle 13.3.2 Loading the Rifle 13.3.3 Running the Bolt 13.3.4 Clearing a Malfunction 13.4 Scope Manipulation 13.4.1 Magnification 13.4.2 Target Focus / Parallax 13.4.3 Elevation Turret 13.4.4 Windage Turret
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14 Spotting 14.1 Making Initial Adjustments 14.1.1 Be Honest 14.2 Determining Bullet Impact 14.2.1 Trace 14.3 Adjusting Bullet Impact 14.3.1 Calling Shots 14.3.2 Adjust to Center 14.3.3 Be Bold 14.3.4 Focus on Hits, not Misses
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15 Zeroing Your Rifle 15.1 Bore-Sighting 15.2 25-yard Confirmation 15.3 100 yard zero 15.4 Slipping Scales 15.5 Mechanical Zero
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16 Alternate Positions 16.1 Sling Use 16.1.1 Cuff-Style Sling 16.1.2 Hasty Sling 16.1.3 Wilderness Cleckner Cuff Sling 16.2 Seated Position 16.2.1 Crossed Leg Method 16.2.2 Crossed Ankle Method 16.3 Kneeling 16.3.1 Heel Rest Method 16.3.2 Side-of-Foot Rest Method 16.4 Kneeling Supported 16.5 Standing 16.6 Standing Supported 16.6.1 Vertical Support 16.6.2 Buddy Support 16.7 Acceptable Error 16.7.1 Perfection Isn’t Always Good
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17 Estimating and Adjusting for Target Distance 17.1 Angular Measurements (“Milling”) 17.1.1 Calculating Distance with Mils 17.1.2 Calculating Distance with MOA 17.1.3 Alternate Units with Mil and MOA Calculations 17.1.4 Measuring Target Size with Mils and MOA Angled Target Measurements
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18 Estimating and Adjusting for Wind 18.1 Determining Wind Speed and Direction 18.1.1 Wind Flags
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18.1.2 Vegetation 18.1.3 Mirage 18.2 Determining the Effect of the Wind 18.2.1 Wind Value 18.2.2 Wind Speed 18.2.3 Additive Effect 18.2.4 “Seeing” the Wind 18.3 Adjusting for Wind 18.3.1 Holding for Wind
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Using the Target Using the Reticle
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19 Estimating and Adjusting for Angles 19.1 Measuring Angle 19.2 Calculating the Effect on Elevation 19.2.1 Cosine 19.3 Calculating for Wind
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20 Cleaning Your Rifle 20.1 Barrel “Break-In” 20.2 Fouling Equilibrium 20.3 Clean-bore/Cold-bore 20.4 Cleaning Instructions 20.4.1 Cleaning Equipment Cleaning Rod Brushes Jags Patches Solvent Solvent Jar Specialty Tools 20.4.2 Regular Cleaning Instructions 20.4.3 Heavy Cleaning Instructions
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Appendix
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Ballistic Tables
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Log Book Targets About The Author
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ACKNOWLEDGMENTS
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I am particularly grateful for the assistance and support from my family.
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To my wife, thank you for helping me finish this book. To my kids, thank you for distracting me and keeping me from
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finishing this book.
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Additionally, I’d like to thank everyone who advised or encouraged me along the way. Specifically, a special thanks is owed to:
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Iain Harrison Colby Donaldson
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Tony Shankle Robert Farago Chris LaValley Trevor Wilson
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1 FIREARM SAFETY
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Firearm safety is paramount. The fact that I included this section before any others should be a testament to my belief in its importance. I wrote this book because I enjoy passing along the information I have learned and I enjoying seeing people fall in love with shooting like I have. I want you to be able to take the information in this book and apply it out on the range. But, I only want you to do so if you are safe. If you are not safe with firearms and choose to disregard this chapter, please pass this book along to someone else. I want to grow a community of responsible shooters.
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Just as there are many techniques and theories to shooting, there are also many versions of the rules of firearm safety. While I do not believe that any of the published rules by other entities are bad, I do believe that they are often too dense. If firearm safety is not tangible to a new shooter, then it won’t be followed. My personal rules of firearm safety are heavily based on the rules of firearm safety from a legend of firearm instruction, Col. Jeff Cooper.
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There are 4 basic rules of firearm safety. The first three rules apply to handling firearms and the fourth rule applies to the use of firearms while shooting. I segregated the rules for handling firearms to help remind you that they apply every time you are around a firearm – not just while you are at the range.
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1.1 Safe Firearm Handling
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Rule #1 – Treat all firearms as if they are loaded If there is a most important rule, this is it. I teach this rule to new shooters like this: “Never do anything with a firearm while using the excuse, ’don’t worry, it’s not loaded.’” If you treat every firearm with respect and you treat every firearm like it was loaded, then
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you’ll never break the other rules. Take note that keeping a firearm’s safety “on” until you’re ready to shoot is not part of these rules. This is because mistakes can happen when shooters rely on a gun’s “safety” as a safety device. Firearm
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safeties are mechanical devices that can fail. Also, reliance on a safety often encourages shooters to break one of the other rules. For example, “don’t worry, the safety is on” is an unacceptable excuse
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for poor firearm handling.
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Rule #2 – Never point a firearm at anything you are not willing to shoot
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I teach new shooters to treat the firearm like it always has a laser pointing down and out the barrel. If they are always conscious of where the imaginary laser is pointing and they never let the laser’s dot appear on anything they aren’t willing to shoot, then they’ll be
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following this rule.
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Rule #3 – Keep your finger off of the trigger until you are ready to shoot
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“Ready to shoot” means that the firearm is oriented towards the target and you are about to shoot - it does not mean that you have showed up to the range and you are ready to go to the firing line and
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shoot. This rule is easiest taught with a training device/non-firearm. Have the new shooter repeatedly pick up and handle the non-firearm until they can demonstrate that they can keep their finger not only off the
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trigger, but also positively aligned with the firearm’s frame. My
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favorite restatement of this rule is … “Keep your booger hook off the bang switch.”
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1.2 Safe Firearm Use
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Rule #4 – Be sure of your target, what is around it, in front of it and behind it.
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Every bullet that leaves your firearm is your responsibility regardless of where it travels. Once you fire a bullet, you can never bring it back. Always ensure that you have an appropriate backstop
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and always think about where your bullet may travel if you miss your target.
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2 HOW TO USE THIS BOOK
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In an effort to organize the information in this book, I have divided this book into three sections: 1) equipment, 2) fundamentals, and 3) application. These sections should help you understand 1) what each piece of equipment is and how it works, 2) the core principles of long range shooting theory and technique, and 3) how to apply what you’ve learned. I believe that this “what it is, how it works, and how to use it” system is the best way to guide you through this information. After all, you won’t be able to use it properly if you don’t know how it works and before you know how it works, you need to know what it is.
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2.1 Format
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This is supposed to be a handbook. This means that I expect you to carry this book with you while you are learning and refer to it as often as needed (I made the cover orange so that it is easy to find in your gear at the range).
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That said, this book can easily be read front to back by someone brand new to long-range shooting. And before you start jumping around from section to section, I do recommend reading through this book at least once.
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Also, please refrain from rushing out and purchasing any equipment until you have made it all the way through the book at least once. There is some information that I cover later in the book that might help guide your purchasing decisions.
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2.2 Website/Supplemental Information
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For your benefit, I have created a section on RyanCleckner.com for this book at https://ryancleckner.com/long-range-shooting-handbook/.
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On this book’s webpage, you will find additional information that accompanies the information covered in each chapter of this book. For example, in Section 20.4.1 of this book, I discuss appropriate cleaning equipment. In the section of the webpage for Chapter 20, I have provided links to where you can find and purchase some of this equipment.
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Also for your benefit, when mentioning another online resource inside this book, instead of including the link herein (which might become outdated / difficult to hand-type into your internet browser), I have included the links in the respective chapter’s section of my website. This way, I can update links on the website without your copy of this book being out of date and you can follow links and view YouTube videos without typing long and completed URLs into your browser.
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Throughout this book, I make recommendations for particular equipment. I think it is important to note that I am not affiliated with, nor sponsored by, any of the referenced companies (although, I’m happy to accept gear for testing … ahem).
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2.3 Feedback
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My website, www.RyanCleckner.com, also has a section where you can contact me with questions, leave compliments, or complaints about the book.
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Because I have decided to primarily offer this book for sale through Amazon.com, I appreciate any reviews you leave there.
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I do understand, however, there’s a good chance you disagree with some of the information I have in this book. This is because some of my techniques and theories are a bit unorthodox. I believe that my unique methods and way of looking at things are what make my instruction effective - of course, you may disagree.
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This is, in part, because this book is not a restatement of standard sniper manuals or teaching. Instead, it is my unique take on the theories and techniques described.
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If you think I’m dead-wrong about something or you disagree with my approach, feel free to contact me through this book’s website. I learn something from every course I teach - I view this book as a course and I might just learn something from you!
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I’ll make you a deal - if you reach out to me and correct an error in this book or help me explain something in a better way, I will include your edits in the next edition of this book and, with your permission, I’ll give you credit in the book.1
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I hope this approach will do two things. 1) I hope it makes us all a community of shooters striving to make each other better instead of tearing each other down. 2) I hope it keeps the internet comment/forum “I’m more tactical than you” pissing contests to a minimum.
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2.4 Sections
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2.4.1 Equipment
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This part of the book is the “what it is/how it works” section. In this section, we’ll cover the terminology, function, and selection considerations of equipment for long range precision shooting. This section includes the following chapters:
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Ammunition Rifles Aiming Systems Accessories Selecting the right Rifle, Scope, and Ammunition
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2.4.2 Fundamentals
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This part of the book is the “basics of long range shooting”/classroom section. I normally teach these topics with a whiteboard or chalkboard. This section includes the following chapters:
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Fundamentals of Marksmanship Units of Measurement Ballistics Environmental Effects
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2.4.3 Application
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This part of the book covers how to put the first two parts of the book into practice. You may not like the techniques introduced in this section. All I ask is that you try them. If you don’t like them, you don’t have to use them. I teach the “toolbox method.” Take a tool I’m showing you and try it out. It may not be useful in all circumstances but you should learn it and keep it in your “toolbox.” Who knows, someday the technique may prove valuable. At the very least, you’ll find a method you don’t like - sometimes that’s just as important as finding a method you do like.
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This section includes the following chapters: Scope Mounting and Setup Shooting Spotting Zeroing Your Rifle Alternate Positions Estimating and Adjusting for Target Distance Estimating and Adjusting for Wind Estimating and Adjusting for Angles Cleaning Your Rifle
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1 Thank you to TJ Sanner, Erich Sagers, Paul Bandy, Eden Neary, David Durra, Travis Jones, and Jacob Hall who each accepted this offer and read this book critically enough to find a couple typos which have since been corrected!
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Equipment
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Generally, a great shooter with a mediocre gun can outperform a poor shooter with a great gun. This is because good performance is more often a product of skill - “it’s the Indian, not the arrow.” Although that aphorism is generally true, a good shooter’s performance can be held back by substandard equipment when it comes to precision shooting.
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An expert long range shooter can shoot up to the performance capability of a rifle. For example, a rifle system (rifle, scope, ammo, etc.) that can shoot no better than a 5 inch group at 100 yards while bolted into a vise will not magically shoot better because an expert shooter holds it while it is fired - contrary to what Hollywood shows us. In fact, the shooter is the least accurate part of a system when quality equipment is used - a high-end precision rifle is more accurate without us.
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You should think about each part of the system, including yourself, as potentially adding variability and decreasing accuracy. I argue that any particular piece of equipment doesn’t actually make a system more accurate. Instead, good equipment can just help minimize inaccuracy.
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Although this might be too abstract of a concept for an introductory book, I think it is important to think about. Unlike with a race car, for example, where a certain part, like a turbo-charger, has a direct effect in increasing the car’s performance, consistency is the key to accuracy in shooting. For example, if the barrel on a rifle is so bent that it shoots bullets at a 45 degree angle, it can still be an incredibly accurate rifle as long as it does it the exact same way every time. The turbo-charger on a car isn’t about consistency, it is all about maximizing output. A faster car is the goal. Quality equipment in rifle shooting isn’t necessarily about performance, it’s about consistency shot after shot
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Consistency is the key to accuracy
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Match-grade ammo, for example, isn’t necessarily any faster or more powerful than hunting ammo. A comparison of specs might actually show that the hunting ammo is “higher performance.” All that matters for matchgrade ammo is that it does the exact (or close to it) same thing every time even if what it does isn’t that spectacular.
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If you think about your rifle system as starting with a baseline of capability, and realize that every other variable can interfere with its consistency and make it more inaccurate, then you’ll be on the right track. For example, a quality barrel locked into a vise is the most accurate baseline. Putting that barrel into an action in a poor stock will decrease its accuracy while putting it into a quality stock will help it retain most of its accuracy. The good stock didn’t give any accuracy to the barrel, it just minimized the variability and therefore minimized the inaccuracy it introduces.
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The same can be said for a shooter. A good shooter won’t make the rifle more accurate. Instead, the good shooter just reduces the amount of inaccuracy that can be introduced by having the rifle operated by a human.
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Having the proper equipment is clearly important. I strongly recommend, however, spending your money on training with serviceable equipment, rather than purchase the best equipment possible and not know how to use it. With $4,000, a novice shooter can purchase an $800 rifle, a $1,200 scope and have $2,000 left for training, ammunition, and some recommended accessories like a sling and shooting bag. That shooter will be a better marksman and more capable with their rifle than someone who purchased a $4,000 rifle and has no idea how to use it.
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These chapters will explore and explain suitable equipment for long range shooting. Some topics will be saved for later in this book or for the sequel to this book, Advanced Long Range Shooting.
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3 AMMUNITION
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Each functional part of a rifle has a purpose and a function related to how ammunition is handled and fired. Heck, the entire purpose of the rifle is to shoot ammunition, so it is obviously difficult to discuss rifles without first understanding ammunition.
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Ammunition is the assembled combination of the following components: a projectile (the bullet), propellant (the gun powder), a case, and a primer. The primer ignites the powder. The powder burns and expels gas. The gas builds pressure which pushes the bullet out of the firearm. This assembled unit is called a cartridge (or a “round” of ammunition). Technically, U.S. federal law treats each individual component of ammunition as ammunition itself.
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The size, shape, and power of ammunition all affect the classification of the cartridge or chambering. Only the ammunition for which a rifle is chambered should be used in that rifle.
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The terms caliber and chambering are often interchanged even though they refer to different things. The chambering, or cartridge, is the entire package. A specific chambering has certain dimensions for its case and overall length, a certain bullet diameter and weight range, and a certain pressure limit. Caliber, on the other hand, refers only to the nominal bullet diameter.
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Source: ATF
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For example, 308 Winchester (308 Win) and 300 Winchester Magnum (300 Win Mag) are two different cartridges. The 300 Win Mag has a bigger case (length and diameter), and therefore has a larger case capacity to hold more powder, its headspace is measured off of a rim around its base instead of its case’s shoulder like the 308 Win, and it operates at a higher pressure. Despite the differences in the overall cartridges, they are both .30 caliber because they both have bullets that are .308 inches in diameter.
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Although caliber and chambering are two different things, I will sometimes use the term “caliber” to describe both aspects of a cartridge because it is the common/every-day use of the term. When someone comes up to you at the range and asks what caliber your rifle is, they almost always are wondering what cartridge it is chambered for. They are expecting an answer like “308 Win” or “300 Win Mag.” They’ll look at you funny if you answer with “.30 caliber” even though it is exactly what they asked.
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3.1 Bullets
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The bullet is the projectile which is fired from the rifle - it is not the entire cartridge. The primary purpose of a firearm is to transfer energy from the firearm to a target.2 The bullet is what transfers the energy.
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Ek=1/2mv2
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The energy that a bullet can potentially transfer to a target is calculated by multiplying half of the mass of the projectile by its velocity squared. This translates to a fast heavy bullet having more energy than a slow light bullet. It also means that speed is more influential than mass when calculating energy. (see Chapter 10 - Ballistics).
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3.1.1 Bullet Design
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A whole book could be dedicated to bullet design and function. In fact, some have been. But remember, this is a handbook for beginners so we will only be briefly discussing bullet design.
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Shape
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The shape of a bullet has a direct effect on its ability to travel through the air and transfer its energy to a target. An aerodynamic pointed bullet can fly through the air easier, maintaining a higher speed which results in more available energy. A blunt-faced bullet, however, doesn’t travel through the air as easily and will slow down more due to wind resistance.3
|
||
It should be noted, however, that although the blunt-faced bullet may have less available energy by the time it reaches the target, its blunt face may help it transfer more of the energy to the target. Think about it like this: a pointed bullet passes through things easier - this includes both the air and targets. A blunt bullet generally resists passing through things, both the air and targets, and therefore transfers more of its energy to whatever it is passing through.
|
||
Bullets come in all shapes, including flat front, hollow point, and even round balls, to name a few. For the purpose of this book, the only bullet shape we’ll discuss is the spitzer, or pointed, shape due to the desire to use aerodynamically efficient bullets for long range shooting. (see Chapters 9 Units of Measurement and 10 - Ballistics).
|
||
|
||
Weight
|
||
The weight (actually, the “mass”) of a bullet has a direct effect on its performance. Bullet weight is typically measured in “grains.” 7,000 grains equal one pound. (see Chapter 9 - Units of Measurement)
|
||
Heavier bullets require more energy to get up to speed (and therefore “kick” more), but they better maintain their speed while flying through the air and are less affected by wind (compared to a lighter bullet at the same speed).
|
||
As a result of the need for more energy to get them up to speed, heavier bullets in a particular cartridge generally leave the rifle at a slower velocity than lighter bullets. This is the trade off in the energy calculation of a bullet.
|
||
For some people, it is difficult to believe that heavier bullets can maintain their velocity better than lighter bullets. As a rudimentary thought experiment, imagine throwing a ping pong ball and a golf ball across your back yard. The ping pong ball will probably leave your hand faster, but the heavier golf ball will maintain its speed longer and travel further. When shooting long range, heavier bullets generally travel farther. The exception, of course, is a light bullet that can be shot at such a high speed that it still stays supersonic at the range you are shooting. (see Chapter 10 - Ballistics)
|
||
Heavier bullets can be affected less by the wind as compared to a lighter bullet at the same speed. Note that this comparison is made for bullets traveling the same speed. If one bullet is traveling faster, then the faster bullet will not be exposed to the wind for as long and will therefore experience less of a shift than a slower bullet. Whichever variable you are focusing on, mass or speed, it is important to note that they both have an effect and attributing a change to only one variable when both have changed (for example, lighter bullets generally start out traveling at faster speeds) may lead you to an incorrect conclusion. Of course, the shape of the bullet also has a significant effect on its drift but that topic is discussed later.
|
||
|
||
Size
|
||
The diameter of the bullet determines its caliber. For example, 30 caliber bullets are nominally .30 inches in diameter and many different chamberings can use the same 30 caliber bullet. For example, 300 Blackout (BLK), 308 Win., 30-06 Springfield (Sprg), and 300 Win Mag can all use the exact same 30 caliber bullet.
|
||
|
||
3.1.2 Parts of a Bullet
|
||
The basic parts of a bullet are the tip, the head (or ogive), the bearing surface (shank / body / sides), and the tail (or base).
|
||
|
||
Tip
|
||
The tip of the bullet is its forward facing point as it flies through the air. The tip of a bullet for precision long range shooting is usually one of three types: full metal jacket, open tip, or polymer tip.
|
||
Full metal jacket (FMJ) bullets are rare in precision shooting. They are durable and easy to manufacture and are, therefore, the most common bullet style in economy-priced ammunition. In addition to being durable while they are handled and fed into the chamber, FMJ bullets are also known for their ability to penetrate without expanding compared to other styles of bullets. This is not desirable when hunting, and as such, FMJ bullets are usually banned for hunting purposes.
|
||
FMJ bullets are rare in precision shooting because of their manufacturing process. It is difficult for the manufacturer to ensure consistency when making FMJ bullets because the process is designed for economy of scale; cheap but not very consistent. These bullets are made by forming a cup of copper around a lead core, leaving the base of the bullet open.
|
||
Open tip bullets, also called open tip match (OTM) bullets, have been the standard precision rifle bullets for a long time. These bullets are not considered “hollow point” (HP) bullets because the opening in the tip of the bullet is a byproduct of the manufacturing process and it is not designed to expand on impact like true HP bullets are. Like FMJ’s, OTM bullets are also formed from a copper cup, but in this case the opening is at the top, which is what causes the open tip, called the “meplat.”
|
||
|
||
If you look at a few rounds of match-grade ammunition with OTM bullets, you’ll likely notice how imperfectly they’re shaped. It always amazed me that bullets with such jagged-edged and inconsistent tips could fly so well.
|
||
The reason OTM bullets are so accurate is not necessarily because of their tip, but rather how they’re constructed. These bullets are accurate despite their inconsistent tips because of the extra care given to quality in the important parts of the manufacturing process.
|
||
Some people argue that the meplat creates a small bubble of air at the nose of the bullet which helps the bullet fly through the air without undue turbulence. There may be something to this argument, but polymer tipped bullets don’t have this feature and they sure don’t seem to need it.
|
||
Some match shooters choose to modify the meplat on OTM bullets to make them more uniform. This can be done by trimming the tips or by squeezing them into a finer point. I’ve never modified the tips of my bullets (but I’m also not a world-class bullseye target shooter).
|
||
|
||
Polymer tipped bullets are a more recent trend in bullet design. A polymer tipped bullet has a larger opening than an OTM bullet and the opening is filled with a plastic tip during the manufacturing process. These polymer tipped bullets can have all of the manufacturing advantages of an OTM bullet but can also have much better consistency in tip shape.
|
||
By looking at the bullets, you might think that the polymer tips are the most accurate because their tips have nice aerodynamic and uniform points. Despite this, match shooters, especially those that are winning, are still mostly using OTM bullets. I believe it is only a matter of time until polymer tipped bullets start to dominate.
|
||
Standard polymer tips can be easily deformed due to rough handling and it was recently discovered that they may be melting at high velocity thereby changing their efficiency as they travel down-range. Hornady has just come out with a new tougher polymer tip material that better withstands the heat from friction through the air. So far, results with these new “ELD” bullets have been great - I’m interested to see where they lead our industry.
|
||
|
||
Ogive
|
||
The ogive of the bullet is the part of the bullet that gradually gets wider from the tip to the shank (or bearing surface or sides) of the bullet. The shape of the ogive has a lot to do with a bullet’s efficiency.
|
||
The ogive is measured by its radius (curve) and is generally either a tangent ogive or a secant ogive. Some newer bullets are a hybrid of both tangent and secant ogives.
|
||
To keep it simple, I’m going to explain the difference in a simple way. If you want an in-depth discussion on bullet shape, please look up Bryan Litz (he’s probably forgotten more about bullet design than I know). The good news is, unless you’re designing bullets, you don’t need to know much about bullet design either - you can just do like I do and choose the most efficient ones, then spend lots of time practicing shooting them. In the military, snipers don’t get a choice of which bullet to use and they seem to be able to do their jobs just fine.
|
||
Imagine drawing a football profile on a piece of paper. The pivotpoint is where you could pick the ball up by its sides with two fingers and have it balance itself. If that’s where the curve of the bullet stopped, it would be a tangent ogive. If instead, the curve of the bullet stopped sooner, then it would be a secant ogive.
|
||
Tangent ogives are common on most bullets. They are not as efficient as secant ogives but they are less sensitive to their position in the chamber when firing (free-bore jump). This is why manufacturers like them - they can make the bullets and be confident that they will perform well in almost every rifle, regardless of how each individual consumer’s rifle is headspaced, or where their rifling starts. (see Chapter 4 - Rifles)
|
||
|
||
Secant ogive bullets can have less than desirable results if they’re not in the exact right position with respect to the start of the lands and grooves. Reloaders who are knowledgeable can set the bullets properly for their rifle during the hand-loading process, but a manufacturer can’t possibly know how every consumer’s rifle will be chambered.
|
||
Hybrid bullets, available only from Berger Bullets (as far as I know), combine the efficiency of secant ogives with the stability and generous freebore requirements of tangent ogives. It is no wonder that hybrids are starting to be the bullets that are winning competitions. It might also have something to do with the fact that Litz is Berger’s chief ballistician!
|
||
|
||
Shank / Body
|
||
The shank or body of the bullet is the full-diameter sides of the bullet which make contact with the rifling in the barrel. This section is also sometimes called the bearing surface. The diameter of this section dictates the bullet’s caliber.
|
||
Some bullets have a band in this section called a “cannelure.” The cannelure is usually a small ribbed band that provides a place for the lip of the case to be crimped into. This is especially desirable on bullets in auto-loading rifles. Without a crimp, the rough loading process in an autoloading rifle can sometimes push a bullet back into a case. This can decrease the internal capacity of the cartridge which can then lead to dangerously high pressures and can cause the cartridge not to feed or function properly. Also, bullets can come loose prematurely and fall out of a case. This is especially true in high recoil rifles and heavy bullets. The inertia of a heavy bullet in a rifle’s magazine makes the bullet want to stay in place while the case is yanked rearward under recoil. To prevent a bullet from being pushed back into or pulled out of a case, the lips of the case are slightly crimped into the bullet, with or without a cannelure, to help the case hold the bullet in position. This is generally not as desirable for precision rifle work, as the crimp is just one more thing that might introduce an inconsistency.
|
||
|
||
Base
|
||
The base of the bullet is more important than one might think. Economy bullets typically have flat bases while precision bullets typically have a socalled “boat-tail” bases that taper in slightly at the bottom of the bullet.
|
||
Boat-tailed bullets allow the air to gently glide off the back of the bullet without creating disturbing turbulence at the bullet’s base. The easiest way to describe this is to ask you to imagine a bicyclist’s “time trial” helmet which tapers back to a point. The same principle applies with bullets.
|
||
This is also a reason OTM bullets can be more accurate than FMJ bullets. Bases on OTM bullets usually have a boat-tail. In fact, another common name for an OTM bullet is “HPBT” which stands for hollow-point (not that kind), boat-tail.
|
||
|
||
3.1.3 Components of a Bullet
|
||
Bullets are generally made up of just two components: the core and the jacket. Exceptions to this are polymer tipped bullets which have a polymer tip, monolithic bullets which are made out of one solid piece of material, and armor piercing bullets which often have an additional material in the core to help them penetrate.
|
||
|
||
Jacket
|
||
The jacket of the bullet is the outer coating which protects the core. Although some bullets are bare lead and don’t have jackets, these bullets aren’t suitable for long range precision work.
|
||
Jackets are typically made out of copper. Copper is ideal because it is strong enough to form a protective shell around the core but it is soft enough to be deformed by the rifling in the barrel. This deformation is a good thing - it’s what allows the rifling to spin and thereby stabilize the bullet in flight.
|
||
Some precision rifle bullet jackets are coated in a dry lubricant called molybdenum disulfide (moly-b or moly). These bullets have a slightly transparent (depending on the thickness of application) black coating. The moly-b coating helps to lubricate the bullet and keep the copper jacket from fouling the barrel. Some shooters swear by, and will only shoot, moly-b coated bullets.
|
||
Source: Hornady
|
||
|
||
Core
|
||
The core of the bullet is, well, the core. It’s the center of the bullet and what makes up most of its mass. For precision shooting, cores are mostly made of lead. Lead is ideal because it is cheap, heavy, and it is deformed easily (both in the rifling of the barrel and also in the target).
|
||
In monolithic bullets, there isn’t really a core - the entire bullet is made out of the same material. In most cases, this material is copper. I see a lot of advantages to solid copper bullets. They hold together better when hunting and I don’t have to deal with lead.4
|
||
A potential down-side to solid copper bullets is their light weight. Because copper is less dense than lead, a copper bullet needs to be longer (it can’t be fatter without jumping up to a different caliber) than an equivalently weighted lead bullet. Also, the majority of competitive target shooters still use lead core bullets - there must be a reason.
|
||
The shape of the core and how it interacts with the jacket can change how well a bullet performs. For example, some bullets have cores that are chemically bonded to the jacket to help them hold together better upon impact. Also, other bullets have designs where the jacket mechanically locks into the core to hold the two together better.
|
||
|
||
3.2 Powder
|
||
Powder is the component of ammunition responsible for accelerating the bullet down the barrel and out of the firearm. The powder is also the source of energy (chemical energy) that is transferred to the target by the bullet (kinetic energy).
|
||
Detonation is the supersonic (faster than the speed of sound) combustion of a material propagated through sound waves. Deflagration is the subsonic (slower than the speed of sound) combustion of a material propagated through heat transfer.
|
||
Modern gun powder does not detonate, it deflagrates. This means that although it can be classified as an explosive under U.S. law in some rare circumstances, it doesn’t explode in the typical sense of the word. Instead, it burns rapidly and builds pressure. The rapid burn of the powder in a cartridge’s case releases gas which builds pressure behind the bullet.
|
||
There are two main types of powder used in rifles: black powder and smokeless powder.
|
||
|
||
3.2.1 Black Powder
|
||
Black powder is the original gun powder and is generally used in antique firearms and muzzle-loading rifles. Black powder doesn’t really belong in a discussion of long range precision shooting. I’ve included it in this book solely to let you know that black powder and smokeless powder are very different and should never be interchanged.5
|
||
|
||
3.2.2 Smokeless Powder
|
||
Modern gun powder is called “smokeless powder.” That doesn’t mean that there isn’t any smoke when a firearm with smokeless powder is fired, but rather that there is MUCH less smoke than when compared to the original black powder.
|
||
Just like with bullets, gun powder is measured in “grains.” The unit of measurement doesn’t refer to each individual piece, or grain, of powder, but instead refers to the weight (actually, the mass) of the powder. (see Section 9.3.1)
|
||
Smokeless powder can be divided into two main categories, single-base and double-base, and then further divided into shape.
|
||
Single-base powder is made from nitrocellulose and double-based powder is made from nitrocellulose and nitroglycerine. The differences between the two types include burning temperatures, velocities, cleanliness, and sensitivity to temperature. It is difficult to say which is better overall because of effects that the variations in shape and chemical additives have on each powder. Single-base powder generally burns cleaner and doublebase powder burns hotter. It is enough to say that both are widely used and a deeper discussion is best saved for another book.
|
||
|
||
As mentioned above, smokeless powder, unlike black powder, does not “explode” if it’s ignited in the open. I put explode in quotes because smokeless powder doesn’t explode in the detonation sense of the term. Instead, it
|
||
Be careful when shipping powder or ammunition. It’s perfectly legal and safe if it’s done the right way. But, it may require special hazardous material fees and considerations. Also, the storage of smokeless powder should be done properly - not only to obey the law but also to be safe.
|
||
Smokeless powder comes in three main shapes: ball (spherical), extruded (cylindrical), and flake (flat). I’ll briefly discuss each, because if you are just getting into long range shooting, you are likely purchasing your ammunition already loaded.
|
||
|
||
Ball Powder
|
||
Ball powder is the worst possible shape for powder. When it is first ignited, it has the most surface area it will ever have. The greater the surface area, the more material is available to be burned. As the balls of powder are burning, they are getting smaller and smaller, thereby resulting in much less surface area. This means that ball powder generally starts with a big burn and pressure spike and then gradually gets weaker and weaker.
|
||
This problem is magnified by the fact that the pressure spike comes when the volume (internal space) of the combustion area is the smallest because the bullet is near the chamber. As the bullet travels down the barrel it creates more space to fill and therefore more gas volume is needed to maintain pressure - this is when ball powder is at its weakest.
|
||
However, if you are reloading, ball powder can be the easiest to run through the powder measure because it flows the easiest and can be started and stopped with a moving gate without being chopped into smaller pieces. This powder measures (meters) very well through reloading machines and I have had good performance results with it.
|
||
There is a variation on ball powder which appears to be slightly squished balls.
|
||
|
||
Extruded Powder
|
||
Extruded powder is the most common powder used in precision ammunition. This type of powder takes the shape of tiny cylindrical sticks. It may not appear as consistent as ball powder, but the accuracy results obtained by using it have proven otherwise.
|
||
My favorite powders, H4895, H4350, and Varget, are all extruded.
|
||
|
||
Flake Powder
|
||
Flake powder is generally found in shotgun and pistol ammunition. It’s easy to manufacture and can burn quickly. Quick burning powder is needed in both shotguns and handguns - often they use the exact same powder. For example, my favorite powder for 45 ACP handgun loads is Winchester Super Target (WST), which is sold as a shotgun shell powder.
|
||
|
||
3.3 Case
|
||
The cartridge case, also sometimes called “brass” due to the material from which it’s usually made, is what holds all of the components of ammunition together. It’s also what’s handled by the parts of a rifle during its cycle of function. (see Chapter 4 - Rifles). The feed lips of a magazine hold the round by the case, the bolt face feeds the round by pushing on its base, the case is extracted by its rim, and the case is ejected by pushing on its base.
|
||
Ammo is sometimes loaded in steel or aluminum cases. Even though these cases aren’t made of brass, you wouldn’t be looked at sideways for calling them “brass.” But if you’re shooting a precision rifle for accuracy, you shouldn’t be using steel or aluminum ammunition. Of course, as with all things in life there are exceptions. Hornady’s Steel Match ammo is one, providing very good accuracy and consistency.
|
||
Most recently, polymer cases are starting to be used, which is an interesting development. Polymer cases are lighter than brass and with the proper care in manufacturing, polymer cases also can have more consistent internal capacity than brass. This means that they can be made more consistently, and therefore more accurately. Also chamber heat may not affect the powder as quickly (a concept we’ll explore in Chapter 11 Environmental Effects) in a polymer case which could lead to better consistency. The downside to polymer cases is that you can’t reload them (yet). The case holds the bullet in the “mouth” at the top of the case and it holds the primer in the “primer pocket” at the bottom of the case. The edge around the mouth is called the “lip” and if there’s an angled portion of the case that gets narrower toward the mouth, it’s called the “shoulder.” At the base of the case is a rim. The rim is used to aid extraction and it is normally recessed into the side of the case. Some cases have rims that
|
||
|
||
extend beyond the case but these are typically found in older rifles or revolvers, which use the rim to keep the round from falling through the chamber.
|
||
The headspace of the cartridge, as discussed next in Chapter 4 - Rifles, is usually measured from the base of the case to the shoulder. If the case doesn’t have a shoulder common on handgun ammunition - the headspace is measured from the base to the lip.
|
||
Some magnum cartridges have a “belted” case. This belt was designed as a method to strengthen the least-supported part of the case while it’s fired, and to provide a spot to measure headspace on rounds that didn’t have a distinct shoulder. 300 Win Mag is an example of a belted magnum.
|
||
|
||
3.4 Primers
|
||
Primers are responsible for igniting the powder inside the case. The firing pin (or striker) strikes the center of the primer (we’re not discussing rimfire ammunition which is struck on the rim) and crushes the cup of the primer against a small anvil inside. Between the cup and anvil is a chemical mixture, usually a lead-styphnate base, that ignites when it is crushed.
|
||
As you can see by the name of the chemical, primers usually contain lead. This burning lead is the most toxic part of the expanding gasses when firing ammunition. Even if your bullets aren’t made of lead, your risk of lead exposure comes from the primer. Always shoot in a well ventilated area and wash your hands after shooting!
|
||
Primers are held in the primer pocket by friction alone in commercial ammunition. Military ammunition has primers which are crimped and then glued/sealed into place. Because of the friction-only hold in commercial ammunition, primers can sometimes come out of the primer pocket during firing. This is due to the pressure on the primer while the powder is burning.
|
||
|
||
The primer cup can deform when there’s too much pressure in the cartridge because the material needs to be soft enough that it can deform when struck by a firing pin. A tell-tale sign of too much pressure in a cartridge can be seen by looking at the primer of a fired cartridge case. If the primer is squished back into the firing pin hole, its edges are flattened, or if it is blown-out completely, there is probably too much pressure.
|
||
|
||
3.4.1 Types of Primers
|
||
Center-fire primers come in two styles: Berdan or Boxer. Ironically, Berdan primers were invented in the United States. but aren’t typically used in the United States. Boxer primers, which were invented in England, are the most common type of primer in the United States.
|
||
|
||
Berdan
|
||
Cartridge cases for Berdan primers have two holes in the primer pocket in the bottom of the case through which flame from the primer travels to ignite the powder (“flash-holes”).
|
||
|
||
Boxer
|
||
Cartridge cases for Boxer primers have a single flash-hole in the center of the primer pocket. Because of the central location of the flash-hole on Boxer-style cases, they are much easier to reload. If you are shooting modern American ammunition, it’s going to have Boxer primers.
|
||
2 The exception to this, of course, is when you are shooting paper targets where the intent is solely to make holes in paper. 3 Actually, “air resistance” or “drag” 4 It is important to note that hunting with lead is safe 5 Except in extremely rare cases where recommended by the manufacturer deflagrates (burns incredibly fast).
|
||
|
||
4 RIFLES
|
||
According to U.S. law at the time of this printing, a firearm is “any weapon … which expel[s] a projectile by the action of an explosive.”6 A rifle is a type of firearm which has a rifled barrel and is designed and intended to be fired from your shoulder.7 From these definitions, we know that a pellet gun/air-rifle is not a “firearm” because it doesn’t use an explosion to launch a projectile. Also, we know that if a firearm with a rifled barrel was designed and intended to be fired from your forehead, it isn’t a rifle.
|
||
Once a firearm falls into the definition of a rifle, it must have a barrel that is at least 16 inches long and and its overall length must be at least 26 inches in order to be treated as a “standard” rifle and avoid certain extra regulations. If either the barrel or the overall length of the rifle are too short, then the rifle is a “short barreled rifle” (SBR) and is subject to National
|
||
|
||
Firearms Act (NFA) taxation and registration. SBRs are generally unsuitable for long range shooting and won’t be discussed here.
|
||
|
||
4.1 Types of Rifles
|
||
The two main categories of rifles for the purposes of this book are manually operated rifles and automatically operated rifles.
|
||
Manually operated rifles require some manipulation by the shooter in order to “cycle the action” whereas auto-loading rifles generally use some of the energy from the previously fired round to cycle the action. The action is the combination of parts of a rifle’s mechanism by which the rifle is loaded, fired, and unloaded.
|
||
Examples of manually operated rifles are: bolt-action rifles, pumpaction rifles, lever-action rifles, and break-open rifles. The vast majority of manually operated precision rifles are bolt-action rifles. This book will not cover the other types of manually operated rifles.
|
||
Examples of automatically operated rifles are: gas-operated and recoiloperated rifles. Gas-operated rifles use the expanding gasses from the burning gunpowder during firing to cycle the action, whereas recoiloperated rifles use the rearward force generated by the bullet’s travel to cycle the action. Gas-operated rifles can be operated by either direct impingement whereby gas is redirected down a tube and pushes directly on the bolt or bolt carrier or by a piston whereby gas is redirected and then pushes on a piston head which is connected to the bolt or bolt carrier. Direct impingement rifles (like the classic AR-15) are lighter and simpler, but their actions become dirtier faster because the exhaust gasses from firing are vented directly back into the action.
|
||
|
||
Automatically operated rifles can either fire one cartridge for every pull of the trigger (semi-automatic) or continuously fire multiple cartridges as long as the trigger is depressed (fully-automatic, full-auto, or machine-gun). Do not confuse “automatic operation” with “full-auto firing.” The vast majority of automatically operated precision rifles are semi-automatic rifles. Full-auto rifles will not be covered in this book.
|
||
Cycling the action generally refers to unlocking the action, extracting and ejecting the case of a fired round of ammunition, re-cocking the firing mechanism, feeding and chambering the next round of ammunition, and then re-locking the action in preparation for firing the rifle.
|
||
|
||
4.1.1 Cycles of Function
|
||
Each step in the process of a firearm’s operation is part of the eight “cycles of function” common to almost all firearms. Each step of this process is important to understand as it will help you learn how your rifle works and diagnose malfunctions. When a rifle doesn’t function properly, it is not simply a “jam” but rather a specific failure to feed, extract, eject, or any other step in the cycles of function.
|
||
You should commit the 8 cycles of function to memory - they are helpful in understanding how most firearms work. I have a mnemonic8 that helps me remember these which starts by taking a date out to dinner (feeding) before bringing her back to your place (chamber), but I’ll spare you the rest. Suffice it to say that inappropriate mnemonics are the easiest to remember - just ask anyone who can rattle off the mnemonic for the 5 principles of patrolling faster than the principles themselves (Ranger inside joke).
|
||
|
||
1. Feeding 2. Chambering 3. Locking 4. Firing 5. Unlocking 6. Extracting 7. Ejecting 8. Cocking
|
||
|
||
8 Cycles of Function
|
||
|
||
The bolt (rifle/shotgun) or slide (pistol) [1] feeds a round from the magazine as it travels forward, pushes the round into the [2] chamber, [3] locks the action as it goes into battery (closed position ready to fire), then the round is [4] fired, the bolt or slide [5] unlocks, [6] extracts the empty shell casing out of the chamber, [7] ejects it out of the firearm, and then it [8] cocks the firing mechanism and starts the cycle from the beginning.
|
||
|
||
A failure to feed can happen when the bolt or slide fails to strip a round out of the magazine. A failure to chamber or lock happens when something prevents the firearm from going into battery. A failure to extract happens when the empty shell case is not removed from the chamber. A failure to eject happens when the shell case is removed from the chamber but it is not “kicked” out of the firearm.
|
||
Each one of these failures is unique. If you just say that you had a jam, it is difficult to diagnose the problem. If however, you say that you had a failure to extract, then we could start by looking at the extractor on the bolt or slide face. When discussing a failure, always refer to the actual symptom so that it is easier to diagnose the problem. For example, a failure to extract will likely also cause a failure to feed. After all, the next round can’t be fed into a chamber which still contains the un-extracted brass from the previous round. Don’t call this malfunction a failure to feed, or your gunsmith will be looking at your magazine and feed ramp and not your extractor.
|
||
|
||
4.1.2 Bolt-action Rifles
|
||
Manually operated rifles, such as bolt-action rifles, can be made to be more accurate than most semi-auto rifles. This does not mean that all bolt-action rifles are more accurate than every semi-auto rifle. In fact, many high-end semi-auto precision rifles outperform most stock bolt-action rifles.
|
||
Consistency is the key to accuracy
|
||
As I’ll repeat often in this book, consistency is the key to accuracy. The less complicated rifle with fewer moving parts is easier to make uniform, making the bolt-action rifle a more consistent rifle than a semi-auto.
|
||
Bolt-action rifles typically come in three action lengths: short, long, and magnum. Short action bolt-action rifles typically can accommodate cartridges up to 2.8 inches in overall length. The most common short action rifle cartridge for precision shooting is the 308 Winchester (308 Win). Long action bolt-action rifles typically can accommodate cartridges up to 3.34 inches in overall length. The classic long action rifle cartridge is the 30-06 Springfield (30-06 Sprg) and a popular long action precision shooting cartridge is the 300 Winchester Magnum (300 Win Mag). Magnum length bolt-action rifles can typically accommodate cartridges up to 3.75 inches in length such as the 375 Holland and Holland (375 H&H) and a popular extreme long range cartridge, the 338 Lapua Magnum.
|
||
Common Cartridge Bolt Face Diameters and Action Sizes
|
||
|
||
Figure 4.1-1
|
||
Many different cartridges share common bolt face diameters. In fact, most rifles, whether short, long, or magnum length action, come with one of four bolt face diameters: 0.384”, 0.470”, 0.540”, or 0.585”.
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Of the four, the most common are the two middle sizes (0.470” and 0.540”) with the largest and smallest sizes used only for a few cartridges on the extreme ends of the scale. See Figure 4.1-1.
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||
If there is too much of a gap between the barrel and the stock, debris can get in the gap. Cleaning out stuck debris can be difficult in the field. A neat method I’ve seen to clean out the gap is to leave a small piece of cord between the barrel and stock up against the receiver. Then, when you need to clean out the gap in a hurry, you can grasp both ends of the cord and pull it forward.
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||
Another reason bolt-action rifles can be so accurate is because they can have truly free-floating barrels. A free-floating barrel does not touch any
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|
||
part of the rifle other than where it attaches to the receiver. This is important because the barrel moves during firing due to harmonic vibration, sometimes called “barrel whip,” that occurs while the bullet is traveling down the barrel. By keeping the barrel from touching anything, the barrel is free to flex/vibrate/whip consistently, without interference.
|
||
Often, a free-floating barrel will be demonstrated by showing that a dollar bill can pass between a rifle’s barrel and stock fore-end all the way back to the receiver. This is not an accurate test necessarily. Often, the barrel will touch the stock during firing/use even though there is a gap between the barrel and the stock while the firearm is at rest. If a stock is too flexible, it can touch the barrel if enough force is applied. Also, if the gap between the barrel and stock is too small, the barrel can strike the stock during firing because of barrel whip.
|
||
A better way to confirm that a barrel is not touching a stock is to take the action and barrel out of the stock and inspect the barrel after it has been used a bit. If the barrel is striking the stock, you should see evidence of contact in the finish on the barrel.
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||
4.1.3 Semi-auto Rifles
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||
With modern manufacturing, semi-auto rifles have become viable platforms for long-range shooting. As mentioned, some semi-auto rifles are more accurate than most bolt-action rifles.
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||
As an example, I had many (too many) rifles issued to me while I was in the military. I had two 5.56mm semi-auto rifles, two 7.62mm bolt-action rifles, one semi-auto 7.62mm rifle, one bolt-action 300 Win. Mag rifle, and one semi-auto 50 BMG rifle. One of the two 5.56mm semi-auto rifles was a highly accurized AR-15-style rifle called the Mk12 SPR. I’m known for loving the simplicity and purity of a bolt-action rifle and also for not being a big fan of the AR-15 platform. In fact, I still believe that a bolt-action rifle in the proper hands can out perform a semi-auto rifle (even during rapid engagements). The Mk12 SPR, however, was the most accurate rifle I had and, therefore, I often carried this amazing performer on combat missions. If I could’ve kept one rifle as a parting gift from leaving the military, it would’ve been that Mk12 SPR.
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I’ve included some photos of a younger me and my Mk12 SPR from Asadabad and Gardez, Afghanistan. In order, the photos below show me and a local in Gardez (this guy was an amazing man), two photos taken on mountains in Asadabad, the suppressor of my rifle sticking out from underneath some camouflage (look for it in the center of the picture pointing left and away), and a photo of my rifle next to my backpacking stove while making some tea in the mountains.
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Although some semi-auto rifles have free-floating barrels, the barrel on a gas-operated semi-auto is never truly free-floated like it can be on a boltaction rifle because it’s inevitably attached to a gastube or piston. The gas tube is usually made of a different material than the barrel, and it heats up and cools down at a different rate. Because of this, the gas tube can cause inconsistent pressure on the barrel. Piston systems introduce a moving part (the piston) within the piston tube attached to the barrel. Although the bullet should have left the barrel before the piston really starts moving, the system introduces more parts and variables into an area where less is better than more.
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4.1.4 Bolt vs. Semi
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||
All else being equal, semi-auto rifles have some advantages over bolt-action rifles. The biggest advantage is that a semi-auto rifle can shoot multiple rounds quicker than a bolt-action rifle, and it can do so without the shooter having to adjust his position. When extreme accuracy is required, however, a bolt-action can be employed just as well as a semi-auto rifle.
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Some scenarios don’t require extreme accuracy. For example, in combat situations a rifle which can engage close targets quickly may be more useful. Also, running the bolt on a bolt-action rifle requires the shooter to move whereas a semi-auto rifle allows a shooter to stay in the exact same position from shot to shot. That is, of course, until it is time to reload the rifle. Additionally, semi-auto rifles produce a less-felt recoil than similarly weighted and chambered bolt-action rifles.
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||
Reloading can be another advantage to using a semi-auto rifle. Many semiauto rifles are fed from a box-style detachable magazine whereas many bolt action rifles are loaded one round at a time through the top of the action with the bolt in the open position. Removing an empty detachable box magazine and inserting another with ammunition is surely faster than loading additional rounds one at a time. However, magazine fed systems are only faster while there are loaded magazines available. Once there are no more loaded magazines, it can be faster to use one hand to drop a single round into a bolt-action rifle and push the bolt forward than to use both hands to reload an empty magazine, then insert it into a rifle and close the bolt.
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||
AR-style semi-auto rifles can’t get as low to the ground as bolt-action rifles with standard rifle stocks. This is because the pistol grip on an ARstyle rifle and the detachable magazine both protrude down below the action. As I’ll mention later in this book, the lower you can get to the ground, the more stable you’ll be. The more stable you are, the more accurately you can shoot.
|
||
Another potential negative to AR-style semi-auto rifles is the requirement to mount a scope higher than is necessary on standard boltaction rifles. This is because the hand guard on an AR-style rifle will
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usually interfere with a scope’s objective lens. The higher the scope is mounted, the higher the rifle’s cheekpiece will need to be in order to shoot the rifle accurately and comfortably. High cheekpieces may not be an option on AR-style rifles because of clearance needed for a standard charging handle.
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The differences in loading time, ability to get low to the ground, and scope mounting height between semi-auto and bolt-action rifles are lessened by the fact that many bolt-action rifles are now being made with (or converted to) pistol grips, AR-style hand guards, and the ability to accept detachable magazines.
|
||
|
||
4.2 Common Parts
|
||
Although the parts described below are unique on different rifles, each rifle has at least one of each of these parts and are common to all rifles.
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|
||
4.2.1 Receiver
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||
The receiver is the part of a rifle that serves as a base to which other parts are attached. Effectively, a firearm receiver is like the frame of an automobile. By U.S. law, the receiver is the only individual part of a firearm that is treated as a firearm. To lawfully purchase a receiver from a manufacturer, you must acquire the receiver from a Federal Firearm Licensee (FFL) and complete a Form 4473 and a background check, if applicable. Every other part of the firearm, however, may be purchased directly from the manufacturer and delivered straight to your home.
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Receiver pictured with bolt for reference
|
||
Some firearms have more than one receiver. For example, AR-15 type rifles have an upper and a lower receiver. In these instances only one of the receivers is determined to be the firearm by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). For AR-15 type rifles, the lower receiver is considered the firearm and in some other rifles, such as the Bushmaster ACR, FN FAL, and the Sig Sauer 556, the upper receiver is considered the firearm. If you’re not sure which part of your firearm is the receiver, look for the serial number. If there’s only one serial number on your rifle, then the serialized part is probably the receiver.
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On bolt-action rifles, the receiver is the central part of the rifle to which the barrel, trigger group, bolt, scope and stock attach. On semi-automatic
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rifles that have two receivers, the lower receiver generally houses the trigger group, magazine, grip, and butt-stock. The upper receiver generally houses the bolt and is the part to which the barrel, hand guard, and scope attach.
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||
4.2.2 Barrel
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The barrel is the tube through which the bullet travels. Just as the receiver is the main part of the rifle for legal purposes, the barrel is the main part of the rifle for accuracy purposes. A good rifle with a bad barrel will not shoot accurately. Conversely, a poor-quality rifle with a good barrel can shoot accurately.
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||
Chamber
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The part of the barrel closest to the receiver is the chamber. The chamber is shaped to house the specific cartridge that the rifle is intended to shoot. During the normal operation of a rifle, the cartridge of ammunition is pushed into the chamber, typically locked into the chamber, fired in the chamber, and then the cartridge case is extracted from the chamber. Because the chamber must contain the energy of the ammunition as it is fired, it is usually the strongest part of a firearm.
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Often, a rifle is said to be “chambered” for a certain cartridge. For example, a rifle that is made to shoot 308 Win. cartridges is “chambered” for 308 Win. The dimensions of the chamber are very important. If the chamber is too tight, a cartridge may neither reliably fit in nor be extracted from the chamber. If the dimensions are too loose, the cartridge may not be supported properly during firing and the cartridge case may rupture.
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Another important dimension in a firearm is the “headspace.” Headspace is the measurement from the bolt-face to a particular spot on a cartridge. Rimmed cartridges like 45-70 Govt. and 22 LR have a headspace which is measured off of the front of their rim. Rimless straight walled cartridges like 30 Carbine and 50 Beowulf have a headspace which is measured off of the front edge of the case. Rimless bottlenecked cartridges like 30-06 Sprg. and 223 Rem. have a headspace which is measured off of a precise point of their shoulder. Rimless belted cartridges such as 300 Win. Mag. and 375 H&H Mag. have a headspace which is measured off of the front edge of their belts.
|
||
Headspace: the measurement from the bolt-face to a particular spot on the cartridge.
|
||
The headspace of a rifle is generally set by how far the barrel is screwed into the receiver on most bolt action rifles or the barrel extension on most semi-automatic rifles. If the chamber is cut too deep, the barrel may not be able to be set in deep enough and the headspace will be too long. If the chamber is cut too shallow, the barrel may not be able to be screwed in
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|
||
enough to support the cartridge case. It is important to have the headspace of your rifle set by someone who is knowledgable. A rifle with an improperly set headspace can be dangerous.
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|
||
Rifling
|
||
After the chamber ends, the rifling begins. Rifling is the spiral grooves in a barrel which cause the bullet to spin. Projectiles are typically spin- or finstabilized. Examples of spin-stabilized projectiles are bullets and spiralthrown footballs. Examples of fin-stabilized projectiles are rockets and arrows. There is also a method to stabilize a projectile by drag, such as by using a streamer, but that method is not relevant here.
|
||
There are two main types of rifling, standard and polygonal. Standard rifling is a series of alternating high and low spots, called lands and grooves, whereas polygonal rifling is in the shape of a polygon. In order for rifling to work, it needs to be small enough in diameter that the bullet must be deformed slightly in order to pass through the barrel. The fit is so tight that a bullet which is stuck in a barrel can not be pushed out by hand.
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||
Just as the chamber of the barrel is dependent on the specific cartridge, the diameter of the rifling is dependent on the caliber. For example, 308 Win., 30-06 Sprg., and 300 Win. Mag. are all different cartridges but they all fire 30 caliber bullets. Therefore, rifles for each of the cartridges will have chambers unique to each cartridge but their rifling will all be the same diameter for the same 30 caliber bullets.
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||
|
||
Twist Rate
|
||
The rate at which the rifling in each of the above rifles twists, however, may be different. Faster or slower twists are required to stabilize different weight, size and speed bullets. The twist-rate of rifling is measured by how many inches a bullet will need travel in order to make a complete revolution. The twist-rate of a barrel is denoted as “1:x” where x is the number of inches required for a full revolution. 1:7 twist rifling is faster (tighter twist) than 1:10 rifling because a bullet will make a complete revolution in 7 inches in the 1:7 twist barrel whereas it will take 10 inches for a complete revolution in the 1:10 twist barrel.
|
||
Twist-rate: the speed at which a bullet rotates measured by the number of inches a bullet travels for each complete revolution.
|
||
As a general rule, heavier bullets in the same cartridge need to be spun faster in order to properly stabilize. For example, 55 gr. bullets fired from a 223 Rem. work well in 1:9 twist barrels. In order to accurately fire 75 gr. bullets from a 223 Rem., however, a faster 1:8 or 1:7 twist barrel is needed. See Section 10.2.7.
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||
Contrary to what you may hear, the twist rate has no direct relationship with barrel length. Twist rate is based on bullet size, weight, and speed only. Although a barrel’s length can affect a bullet’s speed, it is not necessary for the bullet to exit the barrel after a complete revolution. For example, a 1:10 twist barrel does not need to be 20 inches long so that the bullet has two complete revolutions. Instead, a 1:10 twist barrel can be any length. As a note, most pistol barrels aren’t long enough to allow for even one complete revolution of a bullet.
|
||
For a discussion on how to calculate the appropriate twist rate, see Section 10.2.7.
|
||
|
||
Throat
|
||
The spot where the rifling starts in a barrel is known as the “throat.” This is the part of a barrel which starts to degrade first, especially with fast projectiles from magnum cartridges. Degradation of the throat of a barrel is called “throat-erosion.” This part degrades because it is exposed to the most heat and abuse from the burning gun powder, where the bullet is initially forced to rotate.
|
||
Free-bore: the distance the bullet has to travel before contacting rifling.
|
||
To minimize throat-erosion and to reduce deformities on the bullet, a rifle can have progressive-twist rifling. “Progressive-twist rifling” does not have a consistent twist-rate, instead it gradually increases the rate of twist as it travels down the barrel until it reaches the desired twist-rate for the particular cartridge at the end of the barrel. Progressive-twist rifling avoids the abrupt twist in the throat of a normal barrel and instead allows for a gradual increase of twist. This type of rifling is nice to have but it’s more expensive than consistent-twist rifling and not necessary for most cartridges.
|
||
The distance between the throat and where the bullet rests when the cartridge is chambered prior to firing is called “free-bore.” If there is not enough free-bore, the cartridge may not be able to be properly chambered because the bullet will be stopped by the rifling. Even if the cartridge can be chambered with the bullet touching the rifling, the bullet can stick in the rifling when you attempt to unload an unfired round. This leaves you with a stuck bullet in your barrel and loose gunpowder in your magazine. If there is too much free-bore, you may have accuracy issues because the bullet “jumps” from the cartridge too far before it contacts rifling. This can cause inconsistent alignment of the bullet.
|
||
Throat-erosion: the wearing-down of the beginning of the rifling.
|
||
|
||
Contour
|
||
Remember, consistency is the key to accuracy. To help ensure consistency, a barrel on a precision rifle should be free-floated. As mentioned above, this is important because the barrel moves during firing due to harmonic vibration, sometimes called barrel whip, that occurs while the bullet is traveling down the barrel. By keeping the barrel from touching anything, the barrel is free to flex/vibrate/whip consistently without interference.
|
||
Consistency is the key to accuracy
|
||
Another way to help minimize flex is to have a stiffer barrel. The contour of a barrel is the outside shape of the barrel. A thicker barrel, sometimes called a bull barrel, is more rigid and more consistent than a thinner barrel. The downside to thicker barrels is their weight. This is why you’ll usually see target barrels with thicker contours or profiles and hunting barrels with thinner contours.
|
||
|
||
Length
|
||
Barrel length does not have the effect that you might expect on accuracy; a longer barrel is not necessarily more accurate than a shorter barrel. In fact, all a longer barrel does is allow more time for the powder to burn, producing a faster bullet.
|
||
As mentioned above, a stiffer barrel allows a rifle to be more consistent. And, as you know by now, consistency is the key to accuracy. A barrel can be made stiffer by making it thicker or by making it shorter. Think about it this way: imagine holding a 12 inch long stick that is just barely too thick to break in your hands. Now, if a 48 inch long stick of the same diameter were placed in your hands it would be easier to break. This is because you have more leverage with the longer stick. The same principle applies to barrels.
|
||
For years, my go-to rifle has been a 308 Win bolt action rifle with an 18 inch barrel. It is extremely accurate and it usually turns a head or two at the range because of how short the barrel is. Even though it has a short barrel, it can reach out to targets at 800 yards just as well as a 308 rifle with a 24” barrel. Now, my shorter barreled rifle will need more elevation dialed into the scope to hit the same target as the longer barrel, but it will be just as (or more) accurate. To me, the trade off of having to dial up 34 MOA instead of 32 MOA is negligible in exchange for having a handy and portable rifle (See Chapter 7 for a discussion on MOA). And, if I’m shooting at 1,000 yards or beyond, I’m typically going to use a caliber more suited to the task.
|
||
|
||
4.2.3 Trigger
|
||
The trigger is the part of the rifle which is manipulated to cause the rifle to fire. Although the trigger (or trigger shoe) is really only the part of the firearm which your finger touches, the term trigger can sometimes be used to describe the entire firing mechanism. For example, someone might refer to a rifle as having a good or bad trigger. They usually aren’t talking about the quality of the part touching their finger (the trigger shoe) but rather are referring to the pull-weight or crispness of the entire firing mechanism.
|
||
Ideally, a trigger’s break (the point at which it releases the tension) should be crisp and it should have a consistent pull weight. Appropriate pull weight is largely a personal preference of a shooter. A lighter pull-weight trigger is generally desirable when accuracy is concerned because it is easier to fire the rifle without disturbing the sights.
|
||
|
||
Single / Double-Stage
|
||
Triggers (i.e., the mechanism) can be “single-stage” or “double-stage.” A single-stage trigger has one pull-weight and one tactile obstacle to overcome. A single-stage trigger typically has one point of resistance which is overcome when the proper pressure is applied. I have heard people describe a good quality single-stage trigger to be like a candy-cane breaking. Pressure is applied against a steady surface until - “snap” - the mechanism fires (the candy-cane breaks).
|
||
A double-stage (or two-stage) trigger has two mechanical obstacles to overcome and two corresponding pull weights. Typically, the first stage is more difficult to overcome than the second stage. For example, it might take three pounds of pressure to move the trigger through the first stage but only one additional pound of pressure to move the trigger through its second stage. Overall, the trigger takes 4 pounds of pressure to fire, but the first three pounds can be pulled and overcome while the shooter is still lining up the sights. Then, the shooter must only add 1 additional pound of pressure to fire the rifle. This mechanism can give the performance of a 1 pound trigger with the safety of a four pound trigger.
|
||
Do not confuse single-stage with single-action. A singleaction mechanism has one action upon pulling the trigger the hammer or firing pin is released. A double-action firing mechanism performs two actions when the trigger is pulled - the mechanism is “cocked” or charged and then released. Because a double-action mechanism must overcome the spring tension of the hammer or firing pin and it must perform more mechanical steps, the double-action trigger is typically a heavier and longer pull.
|
||
I prefer two-stage triggers. This is partly because I value crispness in a trigger over lightness. For example, I’ve never had a trigger on any of my rifles that has less than 2.5 pound overall trigger pull. If a trigger is any
|
||
|
||
lighter than that, I may accidentally fire the rifle while I’m trying to get in the final steps of firing.
|
||
I like to have a purposeful placement of my finger on the trigger - with too light of a trigger, the rifle can go off while I’m placing my finger in the proper position. In fact, when the trigger is too light, I have more of a tendency to “slap” the trigger because I know that if I place my finger on the trigger to start a gentle increase in pressure, the rifle is liable to fire too soon. Of course, I like “tactical” style shooting and you may prefer a much lighter trigger for bench-rest style shooting.
|
||
With a two-stage trigger, I am able to place my finger on the trigger and apply pressure until I feel the second stage. From there, I only have to add a small amount of pressure to fire. This gives me the ability to “pre-stage” my finger in the proper position while still having a small effort to fire the rifle.
|
||
|
||
Lock-Time
|
||
The lock-time of a firing mechanism is the amount of time it takes from the moment the trigger “breaks” until the round is fired. It is ideal to minimize the lock-time. If the lock-time is too slow, the rifle has a chance to move after the trigger has been pulled but before the round has been fired.
|
||
|
||
4.2.4 Hammer/Striker
|
||
The hammer or the striker of the rifle is what is released upon pulling the trigger. It’s the part of the rifle that is under tension when the rifle is cocked or charged.
|
||
A hammer is released by the firing mechanism and rotates forward under spring tension to strike a firing pin and drive it into the primer of a cartridge. This operation is much like an actual hammer (think tool-box hammer) swinging forward to strike a nail. Semi-automatic rifles are usually fired with a hammer and firing pin.
|
||
A striker is essentially a firing pin that is under tension. A normal firing pin generally sits passively within the rifle until it is struck by the hammer. A striker, on the other hand, is pulled rearward under spring tension and then released when the trigger is pulled. This operation is much like a ball launcher of a pin-ball machine. Bolt-action rifles usually have a striker.
|
||
The striker of a bolt-action rifle is often called a firing pin. This is not necessarily incorrect - just understand that a true firing pin is usually struck by a hammer whereas a striker is basically a firing pin which is pulled and released.
|
||
|
||
4.2.5 Sear
|
||
The sear is the most misused term I hear associated with firing mechanisms. The sear is the part that holds the hammer or striker back until the rifle is fired. By pulling the trigger, the sear is moved out of the way and the hammer or striker, which was previously “cocked” under spring tension, is released. The sear may be a separate part in the mechanism (like in most bolt-action rifles) or it can be a part of the trigger (like in most hammerfired rifles).
|
||
Fully automatic rifles, or machine guns, which are not the topic of this book, can have a second sear that releases the hammer when it is moved by the bolt closing as it returns to battery.
|
||
|
||
4.2.6 Stock
|
||
The rifle’s stock connects the action of the firearm to you. On bolt-action firearms and some semi-automatic firearms, the stock is the piece of wood, synthetic material, or sometimes metal (on newer chassis systems) which has a portion to rest against your shoulder (butt), a place to rest your cheek (comb), a place to grasp with your firing hand (grip), and a place to support the rifle up front with your non-firing hand (fore-end). On some semiautomatic firearms, the butt stock is a separate piece from the fore-end.
|
||
In order to free-float a barrel, the channel of the stock where the barrel passes over the fore-end (cleverly called the barrel channel) is opened up so that it’s larger than, and doesn’t make contact with, the barrel.
|
||
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