So far I have been happy with straight COWWs for 38 special fodder. I plan to play with COWW+ a few % tin for gas checked rifle boolits (target) and 50/50 + tin for hunting rifle boolits. All of this seems to be what everyone else uses and I am certainly not eager to blaze a new trail unnecessarily. I know that 20:1 and similar pure lead/tin blends were used historically. Is there any advantage to the lead/tin alloys over more common lead/antimony/tin blends? My uses are mostly target, small game (with complete pass through and expansion not really desired), and a relatively small volume of rifle rounds out of 357, 44, and 35 Rem levers.