Hey guys, i recently built a 5.45x39 AR15 with because that's the only ammo i could find on shelves currently. I bought a few cases of silver bear steel case ammo and proceeded to let off a few hundred rounds to sight it in and test function. One particular box of ammo was popping primers and being really smoky but i didn't take that as a sign to stop before my upper blew up in my face. The mag flew out the bottom, the upper split and so did the BCG/Barrel. I am done with steel cased ammo in all calibers, who knows when it could happen again? Attached are pics. A friend who is a reloader said they must've filled the case to capacity.