WW is wheel weights - here, they avaerage brinel 13 for hardness. Inother locals or from other supplies, they can be somewhat softer.
: In the .50 cal ctg. rifles, I use 50/50, WW and pure lead with no leading to 2,000fps. The bullets MUST be .002" oversize or they will lead. This seems to be universal for case bullets for rifles as well as handguns. In wheelguns, .001" oversize usually works just fine. Trouble arrises with leading if the bullets are sized to groove dia. and in some, even if .001" oversize. Generally, AS-CAST is the best as rarely does a modern mould cast more than .002" oversize.
: The softer lead (than some people use) continues to press against the barrel walls, to effectively seal off the gas pressures. Hard lead bullets must be oversize initally to maintain a tight fit as they won't slug-up while travelling down the barrel to help with the fit. My loads in .357mag. and .44 mag revolvers use only straight WW metal, without leading. My barrels are smoothly polished to start with.
: In the .50 rifles, I used SPG lube as well as Lyman BP lube for both BP and smokeless loads with clean shooting and great accuracy. Recently, I've started using Lyman Moly stick lube (not the old black stuff they've sold for 50 years) and it too seems to be good. The moly lube is for smokless loads only. For BP loads, use only BP lube.