[Unclenick]

If you load long enough you run into this stuff in various brands. I once bought 1000 new, unprimed IMI .45 Auto Match cases and found the pockets too snug to let me seat primers reliably if at all, and had to swage them, too. If you look at primer pocket specs, they allow ±0.001" on diameter. If you get some on the tight side of that range or off a worn forming die, you'll feel the pinch. It's one reason the Dillon 1050 8-station commercial grade loading machine uses one station to swage every primer pocket whether it needs it or not.