Hi, my dad gave me his Western Auto Revelation 12ga pump (R310AR) that he bought I think in the 60's or 70's. I have looked around online and I guess it was made by Mossberg and is equivalent to their 500AB. It originally had a fixed full choke but he had a gunsmith bore it out to a modified. My question is: what kind of ammo can this gun handle besides lead? He has been shooting Hevi-Shot (not the classic doubles) through it for several years and I can't see any obvious damage. Does that mean I can use steel as well or should I stick with something like hevishot classic doubles for waterfowl? Thanks much for your advice!