Leupold make all sorts of good scopes. 4-12 is certainly plenty for a muzzleloader but that's a personal preference thing.
I've got a 2.5-8 Leupold on mine and I think it's plenty....for me.
Zeke
I'm wondering too.
I do not like the BDC's on my Nikon,but it was only MZ scope on the market at the time.
Friend had a Leupold rifle scope,non mz, on his and it knocked the lenses loose.
I bought the Leupold UltimateSlam 3-9x40mm and put it on the new Remington Ultimate. The mil dots in the scope are very accurate when shooting some distance. I think well worth the $300. I also bought a Hi-Lux 3-9x40 for the old Omega. It looks very nice but I have not shot it yet.