BP type fouling

[ken s]

Ok, new 'old' topic
I'm shooting an original 74 Sharps sporting rifle, in 40 70 SS.
good bore, full rifling. gun is 95% so it should shoot.

load is 64 1/2 Swiss 1 1/2
060 Walters wad, no lube wad
mag primers
330 custom 1 20 Hotch PP with 9# 25% cotton
no compression, slight die crimp to hold bullet
good but not great 100 yd accuracy, clean between shots
great 50 yard accuracy, now trying 100.
BUT..
It fouls badly.
Any thoughts on 2 F, or a different powder brand to reduce fouling?

thanks...Ken