on the gas piston do you know if there is supose to be a ring in the groove cut around the piston near the top? there is a metal ring pushed down at the bottom of the piston so maybe that just poped out?
i tried diferent types and all worked good in it. it just simply stoped working. i tried it 10 times after that, (including using high brass win shot #4, and 2 federal 2 3/4" buckshot) and it still would not cycle the action. and on the last trie, i even had troubles opening the action. and it is not dirtly either. so thats why i think there is something wrong for it just to instantly stop working like that, and i didnt have any problem befor with it.