I have a line on several hundred pounds of foundry soft lead, cheap. They guy sent me a few ingots to try it out, and I cast a handful of .45 bullets last night. They cast OK once I got the mold really hot and the lead at 900°, not nearly as easy to work with as decent WW alloy mixed with pistol range lead. And they still were a *little* wrinkled and didn't have sharp edges.
How much tin do I need to add just to decrease the surface tension? 1%? 2%? I don't need to harden it for .38 Special target loads and .45 Colts, and I that's mostly what I shoot. Then I can save my hard lead for the 9mm's and .357's (etc.) I have a few bars of 60-40 solder, and 25 pounds of "magnum" lead shot, but I think the antimony in the lead shot would be overwhelmed by its arsenic and *increase* the surface tension instead of decrease it (unless I add tin, so why not just add tin in the first place).
I had a pot of hard lead that wasn't casting as easy as it should, and I added just a little bit of solder and it straightened right up. But that probably had a little tin in it already.
Wha'd'ya think?