Markus,
I have seen the damage first hand that steel can do to a barrel with too much constriction. I think shooting Bismuth may be the answer. You are probably right though, I doubt I would shoot enough steel through it to make a difference but I don't want to risk it. I will mostly be using it for coyotes and turkeys with lead or copper plated lead shot. I think I will put it on layaway till I get paid and then pick it up.