New guns are full of cosmoline type greases and junk. Something is in there making it hard to work. I'd look on the youtube and see how the trigger group comes out, the Mossys are super simple. You can have this fixed in 10 minutes I bet. I'd be pulling it all out anyways, mossbergs are notoriously dirty from the factory. While I was in there it would get a new safety tab and a M-carbo trigger spring kit. For minimal $$ you'll never worry again.