I haven't been able to find 4f bp locally, and can't afford to pay the hasmat fees on mail order. So I have been using 3f in the pan of my .54 Cabelas. Works good. If I use Pyrodox in the barrel I have to use 5 or 10 gr. 3f kicker and then 80 gr. of R/S. Otherwise just plain ole 2f. Real bp is not available around here, but found some at a gun show. Not many shows either, so I have to pay attention for them. So far I am not at all satisfied with the shot groups, so have to keep trying. LOL