RE: QD scope mounts?............
I use the Warne QD rings on a number of rifles. They are on weaver mounts. I take the scopes off every time I clean the rifle, replace it and have yet to find the scope move off adjustment more then an inch. So if these Weaver QD rings are good quality there should not be a problem.
As for what distance to sight in will depend on the shooting circumstances you face. If some of your shots might be 100 yards then sight in for that distance. A roundball will still kill at that distance. Especially if placed in the proper place. If your shots are further then that, with a roundball you can stretch it a little more then 100 yards, but you are running into some dangerous area as the ball is really slowing down and loosing energy. Conicals are the same as roundball.
If your shots are closer then 100 yards, say 75 yards, again, that's a good distance. Where I hunt, most my shots are 50 yards or less. I sight my scopes in at 75 yards only because the drop difference is so low. I am then good to all distances and just a little low at 100 should that ever happen. So I aim then for the top of the kill zone..
Good luck and keep me posted as to how well that ball barrel does. I have a .58 caliber that is very accurate and would be a lot of fun with a scope on it.
"Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, a total wreck, screaming Yahoo, with a big smile on your face."