If it were mine, I'd ease open the choke to mod and shoot 1500 FPS #4's. IMHO a 37 is a great gun, but not collector material, so you're not going to hurt the value significantly. These days there really isn't a need for full choke, since lead is banned for waterfowl. My duck gun (which got a workout yesterday) is a M31 Remmy matt rib with a Briley Thin-Wall choke system, shooting their Steel shot tube and the load mentioned above