What specifically is the plaintiff claiming the defendant should have done that (1) the defendant didn't do, and (2) would have changed the outcome?
The Beretta has a loaded-chamber indicator. I don't think it has a magazine-disconnect safety, but such a device won't prevent a firearm from firing if someone puts in an empty magazine. And a gun which couldn't fire with an empty magazine in place would be rather silly since it would make it impossible to shoot the last round.