[quote=BIG AL] The reason for canon powder being so much larger than what we would use is to generate more pressure for the heavy projectile.
I'm not in agreement with that part of your post, BIG AL. I've burned many, many pound cans of black in the last 24 years, and my understanding of the usefulness of different granulations is a bit different. The coarser the granulation the slower the burn rate, and vice versa. FFFFg is used exclusively as priming powder for the pan in flintlocks, and is very fine so that it will "flash burn" quickly and ignite the main charge in the chamber in the shortest time possible. Fg, or cannon powder, burns much slower but does not generate more pressure than the finer granulations. A slower burn is necessary to get the huge projectile moving WITHOUT having an extremely high pressure spike. It is dangerous to use VERY FINE granulations in large bores because the faster burn rate will lead to higher pressures. I've used granulations from Fg to FFFFG, in appropriate bores, with never any pressure problems.
I would also suggest that if you get into making your own that you invest in a set of the brass screens to size the powder. My BP mentor, Jerome Wilson, now passed, had a set that we used to screen Dupont Goex before rifle matches. You would be amazed at the fines, and a smaller amount of coarser granules that we would screen out of a pound of new powder. The uniform granulation which resulted from our screening gave us much more uniform burning from shot to shot, more uniform velocities over the chrono, and tighter groups downrange from our buffalo and bench guns. Well worth the time it took, but always be careful to screen small amounts at a time in a safe location.
Good luck with the project and please keep us posted on your progress.
Stan
