Jim,
I have found straight wheelweight alloy to be about optimum for ductility and penetration. Bullets can be driven to 2000+fps. given correct sizing and lube. They will penetrate just fine, and they are soft enough that they don't shatter on heavy bone. They will shed a bit of weight (usually about 30%), and they will also mushroom/rivet a bit. The few I have recovered show about +25% increase in diameter. In few words, I like 'em! HTH.