Congratulations! Like the others, I'm surprised that bullet stopped in a deer. Must have been quartering away at a pretty steep angle and must have hit the offside shoulder bone? I use the Lee 310 44 caliber with a sabot in my 50 cal muzzle loader and have used 50/50 CoWW/Pure lead with 1% tin added. I was intending to melt those down for something else though to make some from nearly pure lead to get more expansion. But after looking at how your bullet expanded when cast from a much harder alloy I'm not sure I need to change anything.