What comes to mind is: -AMT Hardballer. Bought it in the late 70s. It never did run right. -Early S&W M25 in .45 Colt. Would not stabilize any bullet I tried to put through it. Keyholed targets every time. -PTR 91. Jam-o-matic. Never did get a full mag to run through it. There may be more but these were the real stinkers.