Shrink,
I have a strong preference fer pure lead slugs over BP, but my lead source is of unknown origin and I've never tested it for actual hardness. It's more than soft enough for frontstuffers though, being soft enough to easily dent with my thumbnail. (it's counterweight lead from old Airforce jet movers, I got a ton of it for $10.00 years ago) I mix it with wheelweight, 50/50 mix ratio by weight, for hunting slugs but use it straight for frontstuffers.