A friend of mine picked up a decent 12 gauge Greener with 26" barrels at a local gun show for $400. Apparently, somebody had just sold it to the seller for $250. Odd things happen I guess. Greeners seem to go for somewhat higher prices on Guns International, I've noticed.

It has older British proofs and the flats say "Not for ball," but there is apparently no mention of the chambering. Is there any way to tell without access to a gunsmith?

He sent me this photo: