They are home-cast from a Lee mould. They are a bore diameter conical type bullet with three "bands" to grip the rifling. I roughly measured the bands on one.
Base band dia. = .505
Center band = .510
Front band = .515
The REAL name stands for Rifling Engraved At Loading. The base (first band in the bore) band goes in the bore with finger pressure and the others take a short starter to force into the rifling to "engrave" the bullet.

TUK101,
I have a good supply of pretty pure lead. I further purify it by overheating it than skimming off any impurities that float to the top. I've found the softer the better for most muzzleloader bullets.

Semisane,
I wish deer hunting was legal here with a muzzleloading pistol, but it's not. You can hunt them with a .357mag pistol, but not a .50 muzzleloader pistol. [:@] They did finally add a 45/70 pistol to the legal caliburs - after I traded off my 45/70 pistol barrel for my Contender. [:@][:@][:@]I could break old beer bottles every shotat the local (long since cleaned up and fenced off) dump at 100 yards with that scoped barrel. Recoil wasn't for the weak-of-wrist, but that gun would shoot!
Just from the way that bullet smacks the earthen backstop behind the target and the hole it leaves I'll bet it wouldeasily killa deer at close range!