I have my father's old Model 11 (that's right, no zeroes). It's a pre-steel shot gun and I haven't used it for waterfowling since the lead shot ban. Is this firearm safe to use with the new tungsten, Hevi-shot, etc waterfowl loads? As I recall, the danger from steel came from the hardness, which caused the pressure problems in the barrel. Does the new stuff deform more like lead?