That happens when cheap ammo is being used.. What happens is that the metal casing on the shell splits causing it to expand inside the barrel there for getting stuck inside the barrel.. The easiest thing to do is to pull the pump and at the same time insert some sort of rod inside the barrel to push out the empty casing.. I had that happen to me and I took it to a gunsmith and thats what he did.. Then it happend again so I fixed it my self.. good gun, cheap or possibly old ammo..
So I got the shell out got the barrel off. For some retarded reason I can't get the pin back in for the trigger but I want to take it apart anyway. I'm trying to remove the trigger but you can't do that until you remove the pistol grip which I can't for the life of me do which is supposed to be done with an Alan Wrench from the butt of the grip. It won't budge no matter which direction you turn though I assume you turn it left. I don't want to ruin my gun anymore so I will probably have to take it too a gun smith.