As the bullet moves down the bore, the pressure decreases. But then I found the original spreadsheet I used to draw the charts. The vertical distance between the centerline of the bore and the centerline of your scope. My study on the subject indicates this zero is valid for one barrel length (14.5in M4) firing one ammo type (M855). With all of that said, you can see why I consider the 16 barrel to be a good all-around length, but the 20 is still king for flat shooting. Any energy exerted here transfers to the rifle and through the stock, where it ultimately comes up againstyou. Im glad you like the charts. Never go below 1.2 and avoid values clearly over 2.0. The design stemmed from decades of research and experimentation, with the final specification being a 55gr bullet launched at 3300 feet per second and penetrating a steel helmet at 500 yards. These represent my three favorite barrel lengths for an AR-15. Plus you can save favorites, add notes and more. Likewise, I was under the impression that the original 50/200 zero was actually a 50 yard/200 meter zero. Copyright 1996-2023 AR15.COM LLC. over what ammo or caliber or gun is "best." Punching a hole in a piece of paper is one thing, but actually having the impact cause significant damage is another. Ballistic calculators require an accurate velocity input to be able to give accurate output. If you enjoy the articles, downloads, and calculators on the Bison Ballistics website, you can help support it by using the links below when you shop for shooting gear. Hi Mat, Im Jimmy and really like your information, do you have something similar to the ballistic info or point blank zero on the commercial 308, say from PSA AR10 platform 18 barrel? Introducing the latest products from the worldwide leader in ammunition. If we had an infinitely long barrel then there would be an equilibrium point. On all of the targets, the 100-yard reference always the highest impact point. Amazing is too light a term for this book's content. The difference between a 25/36/50 yard zero is also not that significant at most common defense ranges (inside 200 yards), though, so I honestly think most people make too much out of it. He's a lifelong learner, passionate outdoorsman, and steadfast supporter of firearms culture. But youll get the point. Currently this is the best hunting scope for the money. Twist rate and muzzle velocity give you RPM's. Below are ballistics charts from several different manufacturers. // ]]> // Texas Tech Provost Finalists, Articles B