One might be an accident, 30 is a message. ( "you wouldn't like me when I'm angry" )
actually, alot of the older guns were not very safe, its a very common prob to have the trigger fail so that the contact tip will make it go off. They should work if you hold the trigger, every time you bump it they go bang. Its also not uncommon for a well used framing gun to double. Its very common for a framing gun to go well into the 6 digets nails driven in a year. Most guys are lucky to get 2 - 3 years out of a gun.