Mossberg will put you in touch with a repair center in Texas. Buy a few of them, those guns eat firing pins. The pin that holds the pins in the gun runs in a diagonal direction and is hard to get to, I had to make a special punch.
Better advise would be to sell that POS! It is, in my opinion, the worst O/U shotgun EVER brought to market. I used to do all the repairs for a local range that used the Silver Reserve for a rental gun. They had 5 of them, and I would pick up all 5 at the beginning of the week, and sure as hell, all 5 would be broken at the end of the weekend. They do indeed eat firing pins, and the cocking piece will get hammered from opening and cocking because it is made out of very soft steel. Absolute junk!