That's really convoluted..........but what I do know for sure is that genuine 5.56 MIL-Spec ammo such as IMI chronos faster than commercial 223, like PMC Bronze.
And in some guns, I will get short stroking or failure to lock back with 223 ammo, not with the 5.56.
Thanks for doing the look-ups; interesting info that can easily be taken out of context.
MM
