Originally Posted by meatyrem
I was always on the assumption that either one can be fired through a rifle chambered in a 5.56 NATO. And either one can be fired through a rifle chambered in .223 rem. There is a fella that said one will fire both but not the other way around. So if there is a slight difference, then will it harm the rifle in any way? Or should it be avoided just to be safe?
without chamber and throat drawings right in front of me, I can't exactly tell you the difference. But I do know it's in the length and angle of the throat. If I remember right the 5.56 is a few thousandths longer in the throat, but with a wider throat angle (I'm sure somebody will correct me). Sorta like a very short free bore. But the cartridge case and length are the same