The main problem with fouling in those small caliber rifles, using small charges, is that you don't build enough chamber pressure to insure efficient, and complete burning of even FFFg powder. There are two things you can do to make BP work better in the .32 and .36 caliber rifles:
1. First, screen the powder. Buy some 40x40 mesh Wire screen from
McMasters.com, make up a frame to hold it, and sift the FFFg powder. The clinkers will not pass through, unless you break them down.
Removing clinkers, and anything larger than 40 mesh powder will enhance the burning performance.
2. Use an OP wad IN ADDITION to your PRB in these small calibers. Face it, the balls just don't weight enough to give enough resistance, long enough, to allow for complete burning. By adding either a filler, like corn meal, or an OP wad, you increase the weigh being pushed out of the barrel, and the friction coefficient of the materials in the bore, so that there are a few milliseconds more time for the pressure to rise before the ball begins moving down the barrel. This doesn't sound like much, but those extra milliseconds are all that is needed to increase chamber pressures and burn those granules of BP more complete.
Oh, The range for BP Granules rated as FFFg runs from 24 mesh to 46 mesh. I found no source of screens between 24 and 46 mesh, other than the 40, and that is what I recommend, here. The 12 inch square of 40 mesh screen costs $ 7.33 the last time I looked. :thumbsup: