Dan,

Thanks for the link. Seyfried wrote, " I normally use FFFg in all but the largest bores. The 10s and 8s, with long barrels and heavy shot charges at times will perform best with FFg. This fine granulation may seem inappropriate to some, but it is partly due to the slower nature of our modern powder, when compared to vintage propellant."

As I wrote previously, vintage shotgun or sporting grade black powder was not pressed as densely as rifle grade powder. That meant vintage shotgun powder would burn faster than rifle grade powder of the same grain size. Therefore anyone hoping to duplicate the performance of vintage sporting powder with modern rifle grade GOEX would need to use the next finer grain size, viz. substituting modern 3Fg rifle BP for vintage 2Fg sporting BP.

On a separate note, another shooter sent me some additional references to BP pressure research. In a paper by Noble and Abel published in 1875, the authors give the maximum theoretical pressure that could be generated with conventional BP as 6400 atmospheres or 92,500 psi. This is apparently a little higher than the 86,000 psi they'd measured in an enclosed container because of heat transfer to the container.

The article cited is Researches on Explosives - Fired Gunpowder, by Captain Noble and F. A. Abel, published in
Philosophical Transactions of the Royal Society of London (1776-1886), ISSN: 0261-0523, Volume 165 - 1875, Pages: 49 - 155.

The link can be found through: http://www.journals.royalsoc.ac.uk/
Or you could try: http://www.journals.royalsoc.ac.uk/media...55r81376806.pdf

Also, I'd written earlier that I thought brown powder was made from coconut shells. Actually, it was made from rye grass, and it was called brown powder or cocoa powder, It had less sulfur than regular BP and was used for naval guns during the Spanish American war.

All the best,

Dick