The reason for the stuck cases is the old lacquer coating that was used on steel cased ammo a while ago. It usually didn't happen in AK's and SKS's and other 7.62x39 guns because the case wall is tapered a lot more than the rounds for AR's. the case walls on .223 and 5.56 are a whole lot straighter than 7.62. So on the old lacquer coated ammo, when the chamber got hot, the lacquer would melt and stick to the chamber. Since all of those problems though, most companies have switched to polymer coating and problems have disappeared. Make sure you DONT get lacquer coated and you shouldn't have any problems. I've shot over 1000 rounds of silver bear through my AR with about 150 rounds of that bump firing, just testing the gun, and there is absolutely no abnormal wear on it