Tom: Hunter Specials are solid utility grade boxlocks similar to the Ithaca Lefever Nitro Special but with the arguably superior rotating bolt lock-up. I would establish that you have 2 3/4" chambers, as shooting 2 3/4" shells in 2 9/16" chambers might increase both pressure and recoil somewhat. You are correct that it should be a 37' gun, and Hunter Arms chambered their 16s 2 9/16" into the 40s. In the best interest of your 70 year old wood, I would suggest keeping to 1 oz loads like the Federal Game Shok at 1165 fps and avoiding the 1 1/8 oz 'High Brass' stuff. It should still make a wonderful grouse, quail, and preserve pheasant gun!