Question from Viewer : 223 versus 5.56 Ammo

Q) What's the difference between .223 and 5.56mm Ammo ?

A) There is a small difference between these calipers. The main difference is in the standards off the pressure tested and measured.

You can put .223 Caliber Ammo into a 5.56mm chamber, but not the other way around due to the pressure variances.