I have a 20 gauge built on a 12 gauge frame. It throws hulls 12 to 15 feet, but the bolt will not lock open when fired. It will lock open by hand. It will split 3 out as fast as you can pull the trigger, but fails to stay open when firing any load including heavy loads. I did have a release trigger come apart inside the gun and it took me a while to get it out. I wonder if I have bent something on the inside? Any suggestions? Thanks