Not my gun, but working on for a friend. Beretta 12 ga pump Silver Pigeon, upon firing gun....
1. It has a hair trigger
2. The firing of the gun causes the pump to slide back forcefully and ejects without manually pumping in a new round and fails to feed a new shell up like it should.

So my question is, after looking on line, can I adjust the trigger pull? How or what spring on the bolt isn't doing it's job of controlling the power rocking the bolt back so forcefully. I've had it apart twice and all the springs appear in place and good. I've looked at a diagram of parts and don't see anything missing for parts. In researching the issue, it seems that it is an issue but no one has an answer for fixing the problem. Only 20k or so were made for this model and some parts are difficult to find. Thanks for any insights or suggestions.

With a known problem, I'd check with Berretta. They might know a fix , and might do it for free.