Well, I should clarify. No one shoots M855/SS109 at a competitive NRA-style high-power match, unless their only other alternative is M193.
I'm going to do some further research here. I suspect that the M4 allows greater chamber pressures, but that's just a guess. There could also be some difference in the rifling. I never bothered to check. Now I'm on a mission... LOL.
The newer versions of the M16 have the same 1:7 rifling as the M4, and pressures are based on the maximum for the round. I don't think the Army would spec a rifle that couldn't fire the issue round. Let us know what you find.
Why is that? I do find it amazing, because a 14.5" barrel isn't going to produce the same amount of energy/pressure/velocity. In theory, anyway.
There we go what? I mean - how many naked cherub statues are in America? How many do you see on the streets? There you go!
A 77 grain Sierra Match King fired from a 20" barrel will already be traveling at least 100 fps faster than the same bullet fired from the same cartridge fired from a 14.5" barrel. Once the bullet leaves the barrel the only thing that matters is the velocity difference. Same ballistic coefficient, same rotational velocity, etc. Physics would have to be defied for the same bullet at a slower velocity to go further.
Its ok: The 2a case that currently holds the bottom of "how many examples owned counts as common use" is in the 10s of thousands (50 or so). So its still counts even if you fail to understand the analogy.
