After our successful .22 zeroing and ballistics table confirmation, there is more to talk about. Remember that all that work is good specifically for one rifle with one ammo type at one particular Density Altitude. Nevertheless, that is extremely useful information. With that rifle and ammo you can shoot anywhere in the world with that Density Altitude.
But it is also useful to compare against other ammo you have tested. Looking back at my Aspirin Shoot matches last year, some ammo acts very similarly. Yesterday’s CCI Standard was 7 MOA at 100 yards. At a range of DAs, Wolf and SK were also 7, while Eley Match was always 5.5 to 6. At 200 our CCI was 28, with Wolf and SK at 26 and Eley 23.5 to to 25. Although we didn’t shoot 150 with the CCI, all the other ammo came in at 15 to 16.
Useful information to know if your ballistic app crashes or you are shooting without it.
There’s another fascinating thing about many ballistic calculators. Yesterday our real life shots were very close to what was predicted. What happens if that is not the case? You can plug in your results and the calculator can adjust its trajectory formula to match. That will also predict other distances for which you have no actual information. You now have a custom ballistics table!
Other ballistics trivia: your program is going to ask you some very important questions – distance between center of the barrel and center of the scope. This is scope height and is fed in as an offset, and can be thought of as shooting a piece of paper that is covering the end of the muzzle. Your 1.5” scope height will make the bullet hole 1.5” lower than what the crosshairs see.
You’ll also be asked about bullet shape models. G1 uses a standard bullet shape like a .45 ACP bullet. That’s great for pistols or rifles shooting pistol calibers, but is nowhere near accurate for modern spitzer type bullets. G7 is the shape you want to use. Or, if you’re lucky, the ballistics program has your bullet in its library with an exact shape.
You will also need to know the rifling of your barrel. For virtually all .22s, it is 1:16 – the bullet does one complete revolution in every 16” of barrel length.
Finally, and I can’t stress this enough – you must invest in a chronograph. The prices have come way down on these. Without knowing the exact muzzle velocity of your round, you are putting garbage into the formula – GIGO – Garbage In, Garbage Out. I have seen many shooters look at the manufacturer’s advertised MV on the side of the ammo box. I can guarantee that is not the speed of the round in your rifle. You are just wasting time and ammo if you don’t use accurate info.
So, now, get a ballistics program! Most ammo manufacturers have free ones on line that will work very well. Take the time to program it before going to the range. Now, paper and pencil go in the range bag. You should have wind device that also gives you DA, although some ballistics programs will grab local weather info over the internet for you. Take your time, document everything, and see what happens.
GOOD LUCK!
KatNap Fever! 