Don, I can't see the proofmarks all that well, but it looks to be marked either 16-65 (2 1/2") or 16-70 (2 3/4") inside a sort of sideways horseshoe. That's the more modern proofmark. However, given the gun's light weight, I would not shoot 1 oz American factory loads in that gun. They tend to be pretty hot (have to make old autoloaders function). I'd highly recommend RST 7/8 oz loads for that gun. (I believe they even have 3/4 oz 16's.) About twice as expensive as buying shells at WalMart, but if he's not going to shoot it a lot, a flat will last him a long time--and he's less likely to stress an older gun with those lighter loads. I killed prairie grouse with them earlier this season. They pack enough punch for anything in the uplands, IMO, except maybe longer shots at wild pheasants.
