WW's can, because they contain small amounts of arsenic, be water quenched and or oven heat treated to gain a higher initial BHN. Over time (weeks) they will get the true BHN hardness of the alloy.
Alloys with little to no antimony and no arsenic cant be hardned.
How hard/fast do you think you need to go?
I fire 357MAG past 1600fps from a 6" barrel with a 97% lead + 3% tin alloy (BHN below 9'ish). Slap a gascheck on and i push that alloy past 1750fps in my (micro groove) Marlin 94 44MAG. 94% lead + 3% tin +3% antimony (BHN 12'ish) with a GC i push past 2250fps easy!
Remember that 22LR's go 1200fps all day long and that from almost pure lead and with shallow rifling.
Food for thought:
http://www.lasc.us/Fryxell_Book_Contents.htm