Unless you have a problem opening the gun after firing, I would not try to peen the holes. This is just not a problem and should not present a problem in the future if you shoot sensible shells. This is a very unusual gun, may be a prototype or low production gun. I have no idea why Beretta didn't incorporate the pin type third fastener in their side by sides instead of the Greener crossbolt. It would have saved them a fortune in production cost.