I have some lead that is about 6 BHN.  Is that close enough for muzzle loaders?  Dumb question, I know, but I don't want to stick a bullet the first time.

pure lead is about 5,wheel weights (stick on ) are about 6 and clip on WW lead is 9-11 depending

Now for Mini/Maxi Ball as close to pure lead is better

For patched roundball I've found anything works (within reason) patching and lube makes more of a difference here

FWIW I've shot thousands of PRB WW lead ball through Smooth Bore and rifled arms with NO issues everything from 32 cal rifle to 16Ga roundball smooth bore,I try to reserve my softest lead for mini/maxi ball and cap & Ball revolvers

What you have should be OK for most anything.....maybe a little stiff for cap and ball but probably could work

Keep in mind that different alloys change the weight and size of the projectile from a given mold,with patched round ball this can be accommodated with different patch thickness

What ya gonna be shooting???

I bought an original .36 caliber long rifle and I have a TC .50 Hawken.  I have a bunch more than I will every use for BP, so may sell/trade it.  Thanks for the info.

I like to be able to scratch it with a fingernail.