Shoot Bismuth and save the gun for the long haul. A few short 10 reloads would make that gun a long range killer that will open up eyes for those who think that the 10 is dead.

I would not shoot modern steel in it. I like all my parts where they are and see no need to temp fate. Fingers, eyes and nose. Current factory pressures are too close to twice the pressure that gun was made to shoot and it is about 100 years old. Lot to ask of 100 year old steel to handle that much pressure. If it fails, you will be real close to the failure. Like most of us you still like your fingers, eyes and nose, right? Shoot lower pressure loads and you will enjoy it more and so will your gun.