The other day I'm shooting my FN Hi-Power, using Winchester USA and using up a partial box (a dozen or so rounds) of Norinco (Chinese) ammo I dug out of my closet.
No probs with the Winchester, as usual. When I was almost done with the Norinco, the slide stopped just short of going fully into battery. After dropping the mag, retracting the slide ejected a new round from the chamber, and a spent primer dropped from the mag well. The spent primer was apparently keeping the slide from going fully into battery. All the Norinco primers looked ugly.
Oh well, at least I don't have any more boxes of that stuff (I don't think).