interesting. i aways thought they were interchangeable. i guess not.
ruger mini14 i thought could fire the nato round, but apparently one should not.
I put a few rounds of .556 Wolf 55gr thru a Ruger varminter in .223 and had sticky bolt lift. So while not a true firearms expert I would not put a .556 load in a .223 chambered firearm.
I have a Rock River Arms varminter rifle length upper with the .223 Wylde chamber and I am happy as a pig in slop with its accuracy with all loads.
Ruger Mini-14s are chambered in 5.56mm NATO, so can shoot either 5.56 or .223.
Early production mini 14’s are .223 only. Later production mini 14’s (serial # starting with a “5” or higher will shoot both.
CC