Paper patching a .50 cal TC Hawken

I've seen Mr. Lewis play with his paper-patched bullets and I'm hooked. I want to cast my own lead bullets for my Hawken, but I need some advice on how to order a proper-sized bullet mold for my barrel. Where do I start? How do I determine the correct size for my bore if I'm paper patching?
Cheers,
Grant.

you need to know the bore size, subtract 4 layers of paper, 1 to 2 thousand thick. buy fifty from BACO and a template. i bought PPB492450.