Relative to post #5, you will want to follow this link: http://www.lasc.us/castbulletnotes.htm
Mold bullet weights are usually for Lyman #2 alloy. Harder alloys, like Linotype will produce bullets that weigh something like 6% less or more. Exact numbers will be found at the link site.
You want to keep in mind that there is a different ideal hardness for different bullets, bullet uses, and velocities.
Also, Tin (Sn) mainly improves metal flow and mold filling (cast-ability). Initially (as cast) it produces hardness; but most of this Tin induced hardness deteriorates in about a month's time. Antimony (Sb) induces hardness that increases (precipitates) with age (time over about 30 days); but does almost nothing for cast-ability or makes it worse than casting pure lead.