.223 vs 5.56/nato

[jrobrenegade]

I have heard something to the effect that you can't shoot 5.56 nato in a .223 rifle, but you can shoot .223 in a 5.56 nato rifle. Can someone clarify this for me?

[Malamute]

Theres differences in how they are throated. To muddy up the waters more, some 223 chambers are throated long, so it doesnt matter. Some guns marked 5.56, arent.

This is some info about the chamber differences. Its been a long time since I read it, there may be more answers to your questions.

http://www.m4carbine.net/showthread....er-Differences

There may be other info, I dont recall if/when it was discussed here, there may be good info here as well. Did you check the ammo section or do an onsite search?

[jrobrenegade]

That hotlink was very helpful Malamute, Thank you!

[Drang]

Here is a quote I found in an article on AR15.com:

...Dimensionally, 5.56 and .223 ammo are identical, though military 5.56 ammo is typically loaded to higher pressures and velocities than commercial ammo and may, in guns with extremely tight "match" .223 chambers, be unsafe to fire.

The chambers for .223 and 5.56 weapons are not the same either. Though the AR15 design provides an extremely strong action, high pressure signs on the brass and primers, extraction failures and cycling problems may be seen when firing hot 5.56 ammo in .223-chambered rifles. Military M16s and AR15s from Colt, Bushmaster, FN, DPMS, and some others, have the M16-spec chamber and should have no trouble firing hot 5.56 ammunition.

Unfortunately, the link to that article is now dead. (I think it now resides here: Ammo Oracle)