I hate to disagree regarding the use of used (hard?) and/or wheel
weight lead in a muzzleloader, and of course it is all relative to
what works in each gun, but the use of SOFT virgin lead in a patched
round ball does indeed engrave when seated with the proper sized patch.

I tested this theory after reading some documentation several years
ago by shooting into water to see what the different lead rounds
looked like after patching. The rounds formed with soft virgin lead
had the patching material texture engraved into their surface where
the ball met the land, and the harder lead rounds did not.
Additionally, the patches from soft lead were intact, uncut and had
no burn-out/blow-out spots and shot more consistent groups at all
ranges, with my .54 caliber Bill Large barrel. Best 5 shot groups
(offhand and unrested) were one ragged hole at 25 yards, 2" at 50
yards, and 6" at 100 yards (I threw 2 wide at this range, probably me
and not the gun...).

Granted, this is one of the finest barrels available (or at least
used to be available, Mr. Large has passed on to that firing line in
the sky...), and I patch VERY tight (I recommend this practice for
the best consistency in shooting) with .020 teflon treated pillow
ticking, dampened with water, around a .535 cast and weighed (for
1/10 grain consistency) round ball, and a single cleaning swab
between each shot with a cleaning patch and water.

My test with hard lead went so poorly I discontinued it after the
25 yard attempt (2" groups!!!). I did attempt this test a second
time with a thinner patch material (.015) with the same results, so I
guess my test was flawed somewhat as I didn't go any thinner with the
material than that.

So, that's my 2 cents worth following my VERY unscientific test. I
submit to everyone interested that may not get the consistency in
their shot strings that they think they should be getting, to look at
your fired patching material to determine where (or if) you are
getting cuts and burn-through, and then reevaluate your ball hardness
and patching thickness for fit in the bore. Soft lead tends to be a
little more forgiving where it applies to this condition, making
consistency more achievable.

John
Camp Verde, AZ