[castlebrew]

recommend that you feed it only .223 ammo, as marked on the barrel.

5.56 has similar exterior dimensions, but the brass itself is thicker, and works at higher pressures.

not that you couldn’t feed it 5.56 in a pinch.

my $.02 worth...

[mmanager]

Didn’t know that. This is one of the reasons I posted this question. I have been out of brass shooting for years.

Thanks

[P8riot]

Second that. Don’t use 5.56 unless it says “5.56” on the receiver.