The gun will need to be broken down in order to see the serial numbers on the flat part of both the receiver and barrels, and on the metal of the forend. I'd suggest not doing anything until you get it to the gunsmith-you don't want to force it open. Hope it won't take too much to make this family treasure shootable again but please note it's likely to have a 2 9/16" chamber, very tight chokes, and you'll need to limit the gun to light loads-nothing more than the Federal Game Shok 1 oz at 1165.