I guess I am confused! Are all 50 cal. Thor bullets made of the same material? If so, I don't understand how bullets of the same diameter and weight could be several "sizes" unless some were extraordinary odd-ball shapes - long needle noses, figure 8s with multiple rifling contact surfaces etc. In that case, would 250gr or 300gr bullets be best and, and if there is a choice, what shape is best? Also, should I start with 100 gns Blackhorn and work up in 1 gr increments?