I'd be more concerned about the loose stock than the loose barrels. However, assuming it's a 12 gauge you can't really go wrong shooting Winchester AA Low Recoil/Noise loads through it. They generate about 6,000psi chamber pressure, have a very light recoil and are usually what I'll start an old gun out with.
Steve
PS It's gotta be a beer can (LOL), see if you can get one from a friend of another denomination.

Last edited by Rockdoc; 06/26/13 11:56 AM.
Approach life like you do a yellow light - RUN IT! (Gail T.)