Note from my experience... I have noticed when I rack my KSG nice and slow, it doesnt always feed correctly. If I rack it like I hate it and slam it back and forward hard and fast, it cycles everything from 2 3/4 shells to the Mini Shells. If I rack slow on the Minis, it will almost always fail to cycle and sometimes on standard shells. Not saying you are doing it wrong, but it took me a few times to figure out that my KSG likes it rough. Run a few tubes through like it pissed you off and see if that might be the problem before you send it in.