10 Bore Pressures?

[huntingsgr8]

Can anyone give me a figure for 10 bore pressures with a round ball, or conical? Specifically those heavy loads that would have been used in African guns.

I found these loads on another thread, and they're in the ball park of what loads I'm looking for the pressures of, but I'll take any information regardless of load.

W.W. Greener The Gun and it's Development:
10(.775) Bore - 273grs FFg, 670gr ball, 1600fps

John Taylor's African Rifles and Cartridges
10(.780) Bore - 220grs FFg, 1250gr Bullet, 1500fps

Cartridges of the World:
10 Bore - 136grs, 700gr ball, 1300fps

Print from a Holland and Holland add...smoothbore jungle gun:
10(.775) Bore - 5 drams black powder, 698gr Ball, 1316fps

[Ballistics in Scotland]

It's no accident that nobody, I believe, makes an internal ballistics program which calculates pressure for black powder, and there is a considerable dearth of such in the literature. I have General Journée's "Tir des fusils de chasse", which is one of the best books ever written on shotgun and ball gun ballistics, despite the fact that he served in the wars of 1870 and 1914. It has never been translated or, I believe, reprinted in French, because it is full of tables with symbols that are hard to reproduce, and is too badly printed to photocopy well.

10ga wasn't a popular caliber in France, but he has a table with the following for 12ga. and 37 grammes of shot (i.e. equaling a perfectly fitting ball). I extract the following bits in the format velocity in metres per second/powder in grammes/pressure in kg. per square centimeter. The black powders are from the French government monopoly powder factories, and not a bad powder despite what Greener says:

"Ordinary grade 0 black powder", which he gives as 650 to 650 granules per gramme, possibly a misprint but undoubtedly coarse:

300/4.6/220
350.5.8/310
375/6.5/360
400/7.3/420

Then for the "Strong No.2" grade of powder, with 4000 to 6000 granules per gramme:

300/4.1/355
350.5.2/480
375/5.8/535
400/6.35/590
450/8.1/670
500/10.3/750

The tables continues to the various government smokeless powders, mostly quite conventional in their nature by that time. They give comparable results and pressures in the more usable loads, but as we would expect the pressure escalates more than with black when the charges are heavy.

It is quicker to look on the internet for a metric conversion site than to multiply by the conversion figures I could give you.