Have been loading 219 Donaldson Wasp with Hodgdon H335 behind Hornady 50 SPSX. Velocity is averaging 3575 fps and groups as good as 3/8 inch.

But this load produces the dirtiest barrel in just a few shots have ever seen. Really heavy gunk.

Anyone have a recommendation for another ball (spherical) powder for the 219 ?

Hammer

Try about 28 grs. of IMR 4064.

4064 is NOT a ball powder...

BL-C(2) From 25.0 grains to 28.8 grains
Remington 9-1/2 Primer

H-380 From 27.7 grains to 31.7 grains
Remington 9-1/2 Primer