The Buffalo Arms molds are very good. I mostly shoot black powder target rifle matches in the states ( mid and long range ) and Buffalo Arms molds are used by most of the top finishers these days.
I don't have my load data for my Winchester 1885 BPCR anymore as I sold the rifle to focus on my Shiloh's, but I remember that mine liked the 535 Buffalo Arms "money" bullets in .459" diameter, cast in 16:1. I also got great results with a Steve Brooks Creedmoor bullet which was 0.460" in diameter and had two reduced driving bands allowing the bullets to be seated out a bit for greater powder capacity.
Have you done any casting before this? If not that'll be one of the bigger learning experiences. Just make sure that you use an appropriate alloy. 20:1 would be a great place to start with the Postell bullet. Don't try making your own bullet lube. When I got started years ago I went down that road and it's just one more thing that'll slow you down while you are trying to get this stuff figured out. SPG lube is good, but I like DGL better as I often shoot in hot weather. Alberta Schuetzen Lube also works very well.
Another thing to think about, at least when comparing this type of reloading to smokeless, is that you want only a very little bit of neck tension, or even none at all. I sometimes use zero ( i.e. the bullets are a snug fit in the case, but you can seat them with just finger pressure, but most of the time I use annealed brass and about 0.001" of neck tension. You can buy custom expanders that fit your reloading dies from Buffalo Arms for this. They are pretty cheap. If you use too much neck tension you'll likely distort your bullets as you seat them. The expander plugs in a standard set of RCBS dies will give you too much in my opinion.
I'm sure you'll have a pile of fun. One other thing I'd say is don't wait too long to start shooting matches. Once you have even a half way decent load then get right into it. You will learn more at your first match than in an entire year fooling around at the range.
Chris.
