For what it's worth, Power Pistol meters just fine. It's no ball powder, but it doesn't present any problems. I have no doubt that W231 is probably "better" but good enough is good enough.
I'm sure whatever is easier to get will work just fine.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.