if it wasnt a broke secondary shell latch i would say it might be a result of the higher powder load in the slug and buck shot does it happen when you are shooting target loads?? also is it always doing it when the gun is full 5 rounds? i hunt in indiana and all the law allows is 3 in the gun anyway what are you planing to hunt? if you also live in a shotgun state like indiana and you are wanting to hunt deer i only use slugs (buck shot is ok under 25 yds buy after that it leaves a lot to be desired so leave it at home for protection heehee) and have only needed 1 shot but i use use a bolt action slug gun (mossburg) 3-1/2" mag load used to use a mod barrel hi standard auto and was not happy with shot placement for a sold kill it was ok just not good and some times it took more than one shot but loved it for clays crow doves or ducks tukeys talaban ect so hope you have fun