Pure Lead (BHN 5) is most often used in black powder guns. By the way, those tape-on wheel weights are almost soft enough to pass for pure lead. Separate them from the clip-on wheel weights.
30:1 (97% lead, 3% tin)
20:1 (95% lead, 5% tin) lead-to-tin is often used with black powder cartridges. It casts well and doesn’t mind a little heat.
Wheel weight (95.5% lead, 0.5% tin, 4% antimony, BHN 8 – 12) My favorite alloy. Compared to other alloys, wheel weight is not as sensitive to mold venting or casting temperature. In fact, wheel weight seems to prefer a fairly warm mold. It may seem uncooperative at the beginning of a casting session, but once the mold has warmed up it usually provides 100% yields. Heat-treated wheel weight will remain usefully hard for a good 18 months. While many people like to add tin to wheel weight, I have never found it necessary. In fact, the best wheel weight is the kind that has zero tin (since I throw my test bullets back in the pot and recycle the pot for months at a time the tin eventually burns off). Tin-free wheel weight is extremely resistant to shrunken bullet syndrome.
WheelWeight + 2% tin (94% lead, 2% tin, 2% antimony) The added tin makes the bullet shiny, increases hardness slightly and may improve fill on small and medium caliber bullets. On heavy big bore bullets, this alloy seems to be more susceptible to SBS than straight WW, and may produce smaller diameters, though no two molds behave exactly alike.
Lyman #2 (90% lead, 5% tin, 5% antimony BHN 15) I used to wonder why anyone would want to use Lyman #2, since its high tin content makes it a spendy alloy. OK, I finally get it — Lyman #2’s hardness is just right for many applications and it is moderately resistant to shrunken bullet syndrome. Unlike heat treated wheel weights, you don’t have to worry about the hardness wearing off after a couple of years, so it’s a good choice for big bore loads that need a long shelf life.
50% Lino / 50 % WW and similar blends (90.5% lead, 1.75% tin, 7% antimony, BHN 16 – 18). This is my favorite alloy for small rifle bullets yet it can be a very problematic alloy with heavy bullets. It is just the right hardness for many applications and fills out well as long as the mold does not get too hot. And that’s the catch — heavy (400+ grain) bullets will usually make the mold hot and then this alloy will produce frosty, shrunken bullets.
91/3/6 (91% lead, 3% tin, 6% antimony). Casts well as long as the mold does not get too hot, but very prone to shrunken bands.
Linotype (86% lead, 3% tin, 11% antimony, BHN 22) is a eutectic alloy with a low melting temperature and excellent fill properties. It is quite resistant to shrunken bullet syndrome, but it is prone to voids in or near the base of heavy bullets. Also, it takes longer for the sprue to solidify, due to the low melting point. Pure linotype is brittle and may shatter if it hits a hard target. It does make a good base for cast softnose bullets.
Bullet Hardness is an ongoing debate. One camp holds that the bullet should be soft enough to ensure that the bullet will obturate. These folks believe that excessively hard bullets may cause gas cutting, leading, and poor accuracy because the bullet does not form a good gas seal. And this is true if the bullet diameter is too small. The hard bullet camp holds that hard bullets give more reliable penetration, and obturation is not necessary if the bullet diameter is chosen wisely. Personally, I tend to use heat treated wheel weight for everything except muzzleloaders.
For hunting, even pure lead penetrates pretty well on flesh but soft bullets may splatter or ricochet if they strike big bones. Bob Milek wrote a story about shooting a black bear at point-blank range with a soft cast bullet — WW + 2% tin or something similar — and the bullet just bounced off the bear’s skull. For big game, I prefer a hard bullet to ensure reliable penetration. Admittedly, hard cast bullets do not create massive tissue damage, especially on soft targets like the lungs, so bullet placement is critical. The heart is always a good target.