Oh brother....getting old, forgetful and easily distracted has its moments...and can be embarrassing. When I read Raimey's post about the 20 bore I thought, "that's ok if it is, not a problem". Forgetful and distracted....lol!! I was in the shower while ago thinking about that and remembered I asked the seller if he knew if the chamber was 2 1/2 or had been opened to 2 3/4. His exact words were, "I don't know but a 16 gauge shotgun shell will chamber and the action close on it". I think it's a 16....surely...

NRA Benefactor 2008
NRA Patron 2007
NRA Endowment 1996
NRA Life 1988