Headspace is the same, leade is longer in the 5.56.
Pretty sure Colt chambers all their guns 5.56.
The barrel marking is the key, not the lower.Yes, even the early ones marked ".223" on the lower receiver.
32. There is essentially no difference between commercial .223 and military 5.56 ammo. The same is true with .308 and 7.62 ammo. The military stuff has slightly thicker brass with a tiny bit more length in the shoulder and I hear this is for strength when feeding through full-auto guns that tend to slam the rounds into the chamber violently. But otherwise, there doesn’t appear to be any difference that I have noted after many years of shooting both military and commercial ammo through my .223 and .308 rifles, both bolt action and semi-auto although with some guns with tight chambers closing the bolt on military ammo can be a bit snug. It is a popular misconception that military 5.56 ammo is loaded to higher pressures than commercial .223 but it is not.
taozen79 0842 CST said:5.56 verse 223 question
I have a ar15 A1 , I believe, colt upper , barrel marked
C MP C
can it shoot 5.56??????
THANKS for any help
Buddy
taozen79 0916 CST said:HELP 'bumped"
HELP
It is a popular misconception that military 5.56 ammo is loaded to higher pressures than commercial .223 but it is not.