mike.44,
Had you tried any other powder before settling on the Blackhorn.
I had recently purchased some Pyrodex P for my flintlock rifle and then found out from others that it's hard to light in a flintlock.
When I ordered the Optima, I figured I could use the Pyrodex P in it. However, the P is a fffG equivalent and the manual for the Optima calls for ffG only.
I thought about using the P at a reduced load but am leary of doing so.
I've always used the fffG blackpowder (the real stuff) in my flintlock rifle and my Ruger cap and ball pistol with no issues.

Jeff