There are a number of different ways to regulate bullet hardness, but one of the best ways is to use a consistent alloy. One of the most popular alloys for those who need a bullet harder than wheel weights provide is Lyman Alloy #2.
Lyman Alloy #2 is an alloy of 90% lead, 5% tin, and 5% antimony. It can be purchased in bar form from a number of places (like Rotometals), but that gets a bit expensive. So here are two recipes for mixing up 10 pounds of Lyman #2 equivalent on a budget:
- 9 lbs of wheel weight lead (clip-ons, not the stick-on ones)
- 1 lb of 50/50 lead/tin bar solder.*
- 4 lbs of linotype
- 1 lb of 50/50 lead/tin bar solder.
- 5 lbs pure lead (here's where you can use those stick-ons)
So what's your favorite recipe?
* I buy mine on ebay. No, really. Watch carefully and you can occasionally get mangled bars for below melt value.
Source: Lyman Casting FAQ.