Mixing loose and pellets is not a good idea. If you want to get different pellet charges, then look at some of the 30 grain and 50 grain combination. Personally I would just shoot the loose powder. Triple Se7en 2f or APP 2f even Pyrodex RS is all said to shoot well out of the rifle.

As for your scope question, I do not own either of them. Let me ask you, what kind of ranges are you looking at when you hunt? Do you need a BDC in the scope? Both of them are great scopes. I personally like the Nikon better. I hunt Nikon Pro Staffs on three of my rifles. As for the rings, all I will use is the Warne QD rings on my rifles. They work perfect. And I broke one. My fault mind you. Warne had me send it back and they sent me a brand new replacement.. free of charge. I am sure that Leupold would do the same. I just like the Warne.