Thanks for the input, Yondering. Fortunately, I now have a better handle on some of my 'unknowns' . I took a sample of my lead pipe fittings and monotype to a local salvage yard where they did a RXF(?) analysis of them. The fittings are 98%+ lead and 1.5% antimony with traces of other metals. The monotype is 80% lead, 12% antimony, and 7% tin. I shouldn't have any problem with having the right amount of antimony, just have to alloy the stuff properly to get enough tin for good fill out. The comment about coww alloy hardness giving good expansion at my desired velocities gives me a target BHN to shoot for.