I use 20 grain of cornmeal by volume.
That's the way I interpretted it when I read it. Thanks for clarrifying.
Look forward to reading your cornmeal test results using them RBs. Who knows, maybe it will even help a bit with accuracy out of that large smoothbore you have. Was that smoothbore a .62 or something?
Anyway, I remember reading the post where you shot a piece of wood with that canon of a smoothbore...the ball looked like a silver dollar

Nice.