That is exactly what happened to me; m1 carbine. From then on, I don't touch their stuff if they pay me.My Magtech experience involved 30 Carbine ammo. Several times in a box of 50, primer fell out of the fired brass. I discovered it when a primer ended up in the left bolt lug recess and prevented it from going into battery. Never happened with any other brand.
Since my Taurus PT92 happens to be next to me as I look at the breech photos, I had to look at the Taurus breech. No concave on mine, and it doubt it helps feeding.