Hi, again, Greg. Personally, I don't like using high magnification on a smokepole. A 3X9 scope is great all around glass for a modern rifle, but more than you need for a muzzleloader... at least in my opinion.
For years I have used Leupold 4X fixed power scopes on some of my favorite rifles including a couple of .22s. The 4X is all you need on deer sized animals inside 150 yards. The Leupold M-8 4X sells for about $220 at Cabela's. I have spent many years in hunting camp and never heard anyone complain about having Leupold glass on a shooting iron.
I have had good luck with the Nikon scopes. For a muzzle loader, I think the 1.5-4.5X shotgun scopes would work pretty well. These scopes are in the $240 range at Cabela's.
If you feel the need for more serious magnification, you could go 2-7X. What would help me is to know what you are hunting and where. In the west, many guys like the higher mag. In the east where a fair amount of hunting is from stands, guys like the easier target acquisition of 1X or 2X at the low end.
Don't worry... keep asking questions and we'll spend all your money.
