People seem to think that slugs are the Hammer of Thor but it's mostly myth, legend and wishful thinking. Fact is, they have terrible sectional density and their shape is not conducive to straight line penetration. The old swaged Foster style slug is awful and actually has less sectional density than a round ball and is good for nothing bigger than deer. The Black Magic is better but still lacking. I tested them in SIMTEST and they penetrated the same as a standard 1300fps 250gr .44Mag load from a revolver. The best revolver loads penetrated nearly twice as deep. Shotguns are oft-recommended not because they are the best tool for the job but because they are cheap, plentiful and most people already have a 12ga pump. They 'may' work fine but they're far from ideal. A properly loaded big bore levergun in .44Mag, .45Colt, .454, .480 or .45-70 is a better choice.