Originally Posted by groper
well i thought it would be a simple as 1 MOA (minute of angle = 1/60th degree) of rifle barrel angle movement = 1 MOA of movement on the target (= 1in @ 100yds)?
Or 1 Milliradian of barrel angle change = 1m @ 1000m bullet impact change.
why does it need to be anymore complicated than this?
if your looking for what it means in terms of muzzle distance movement instead of barrel angle movment, simply scale it down to the barrel length. So if you move the muzzle by 1 MOA and say your barrel is 30in long.
1 MOA = 1in @ 100yds
= 1in @ 3600inches
= 30/3600 (barrel length divided by distance)
= 0.0083 inches at muzzle = 1MOA = 1inch at 100yds.
groper - that's pretty much what I needed. Maybe an explanation as to what I want the information for would have helped the responses.
I am getting frustrated talking to shooting friends about guns and group sizes: i.e. friend "x" who is fairly new to rifles (not guns but rifles) works on a load and goes to the range and shoots his first ever 1/2 inch group with a gun I built for him (light barreled hunting rig in 300WSM). Off the bench with a bi-pod. Great - happy as a ....
Now back to the range another day and he shoots over an inch - my phone rings with "what do you think could be wrong with the gun? It's shooting all over the place."
Well he's a very good friend so it's hard to just throw out there that perhaps the fact that you have only ever shot one 1/2 inch group in your life might make you think it is operator error
SOOOO, I hint about things like "do you realize how little it takes to open up a group from a half to one inch? How tiny the movement really is? Or the fact that you shot the good group on a calm day and this on a windy day which can open it up that much. The fact that bi-pods can react differently when on different surfaces like a wood bench versus concrete - or you can torque the legs while positioning and then they "jump" when you shoot. Or maybe the original group you shot being only 3 rounds was actually a fluke - should have shot 5 rounds at least. Or your loads aren't that consistent. And on and on...ect. ect. ect....
Just looking for a pleasant way to let him know it usually isn't the gun at that point.