As far as powders, you would be good with either ffG or fffG. I have several 45's, most are caplocks, but a few flinchlocks, and they shoot a little better with 3f, especially if you are using light round ball loads. BTW, I found that in all my 45's, accuracy deteriorates rapidly with loads over 70 gr. For caps, no. 11 are the standard, but 10's will work just as well. No need for the more expensive "magnum" caps, in my experience.