Which scope would be best for a muzzleloader with 150 grains of powder? Lets keep the price range under $200!

You can buy Nikon Pro Staff 2x7x32 about anywhere for $125 plus or minus a few bucks. I have them on all three of my muzzleloaders and two slug guns
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Lots of good choices for muzzy scopes for less than $200. I caught a sale on Cabela's a couple of years ago when they discontinued their old line and got good scopes for about $60 each, marked way down.
Don't be stuck on the 150 grain charge. Try different loads. We usually shoot 80 to 90 grains and have good luck.

Take a look at Elite 3200. Should be right at your upper limit of spending. I have a 4200 and really like it. Guessing the 3200 is a good scope for the $$$$ as well. Go to "Bear Basin Outfitters" for a quick look at typical pricing.

You ought to look at the Vortex Diamondback, great scope and very clear and crisp. Great warranty as well.