[Ol' Dan Tucker]

btw,.223 ammo is considered less powerful than the military 5.56mm ammo. Some manufacturers of .223’s will warn against using 5.56mm ammo in a rifle chambered for .223.

The recommendation against using 5.56mm in a rifle chambered for .223 has to do with different headspace, not intrinsic power of the round.

The 5.56mm is slightly longer and when fired in a .223 rifle the bolt may not fully lock.

[OldArmy52]

Thank you for the correction!
Our goal here is accurate info.
Thanks for your post!