Get a rifle you can shoot NfB loads in, either a 450 or 500 late black powder gun. They are a lot of fun to shoot, easy and cheap to load for once you do some reading, can take anything in North America and don't kick the crap out of you. They are the best of both worlds. I have three, a 500 3", 500#2 and a 577 3" and enjoy all three. You will most probably have to plan to reload as it allows you to find a load/bullet that works best in your rifle but it's part of the fun and no huge chore. Get Graeme Wright's "Shooting the British Double Rifle" and read it a few times, particularly the chapter dealing with the NfB loads.
Best.