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[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

Hal or anyone else:
Would you please elaborate on the pyrotechnic display to be held in Fargo next Month?
Jim

If you think about what you just wrote you will see that my statement is correct. The burn rate is a time event. Once you have ignition till the burn is completed, the gases stop expanding, the event has concluded. The longer the event the more pressure. This is called barrel time. Yes indeed this is controlled by grain size and shape. Not to much different than with progressive burning powders, which both types really are.

I totally agree about screening the powder and that was the last part of the puzzle for me and was covered in the previous post.

I suspect it will take several batches to get enough of each size that I need, to get all the powder I need.

Thank you for your feed back.

I think I'll make some black powder

A vary good read with lots of pictures.

Maybe we are on the same "page" but just wording it differently. All my best.

Stan

If you consider the fact that all the BP granulations are composed of the same mix, they then contain the same energy for a given wt of powder. The granulation controls the rate of burn. A fine granulation gives a higher pressure for a shorter time & vice versa, other things being equal. A "too fine" granulation behind a "too heavy" load could result in a "too rapid" rise in pressure creating a dangerous situation. The burn rate should however relate to load density rather than bore dia. Thus a very heavy load in proportion to bore also requires a slow burn rate. With round ball guns sectional density goes up in proportion to dia so a larger caliber required a slower powder. Shotguns have more commonly been loaded with a similar load density for the various gauges so generally used the same basic granulation, exceptions being sometimes found on both ends, ie extra heavy loads were often used in both the very large bores as well as in the very small ones, but for different reasons of course. Both would then require a coarser granulation than normal.

It is the annual convention of the Pyrotechnics Guild International, Inc. We have seminars, workshops, product demos, sales of chemicals, pyro-related items, etc. Main thrust is to let amateur fireworkers compete in all the different types of homemade fireworks (shells, mines, comets, etc). Within these types are classes based on size and difficulty of making the items and getting them to perform as they should. Many people come with their families just to buy and shoot consumer fireworks or watch the big shows each night culminating with the Grand Public Display on Friday. I hosted this convention twice in the '80's, but now we do not have enough motel rooms. More info at http://www.pgi.org