How much does a barrel of gunpowder cost?

The Old World Armoury for Warhammer Fantasy Roleplay (second edition) says that gunpowder is sold in "small kegs" and costs 3s per shot, but how many shots are in a keg? I can't find the answer anywhere in the book.

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seems like the GM could/should just define the keg size sold by a specific vendor, I think. and if someone buys, let's say, 3 kegs of 50 shots, they would just add 150 shots to their inventory – nonchip Feb 25 '14 at 9:50
@nonchip +1 for a great, bare-bones, abstraction. I'm a WFRP GM (and admittedly a zealot) so I took it to the next level and filled in the blanks of the Old World Armoury below. – javafueled Feb 25 '14 at 15:23

Historical notes

After some light reading in several top ranked Google results, a phrase buried in the history of 18th and 19th century British artillery pages stood out: "dry and tight cooperage."

This in turn led me to the usenet group rec.pyrotechnics and an interesting post that "cribbed" the New Scientist regarding something called the Barrel Boom:

Gunpowder barrels were made of oak by a tight cooper and were actually good enough to hold liquid. The hoops surrounding the staves were of copper and wood, which are non-sparking, never of iron or steel. Standard full barrels contained 100 pounds of gunpowder, half barrels 50 pounds, and so on down to 2-pound barrels for sportsmen. When filling the barrels, space would be left to allow the powder to move freely. Regularly rotating the barrels would then prevent the powder from aggregating during storage.

A two (2) pound barrel is a "small keg" for the "sportsman" (or typical WFRP gunpowder user).

WFRP notes

The Old World Armoury, as noted, states gunpowder is 3s per shot. The challenge then can be mathematically abstracted for WFRP: How many shots in a 2 pound small keg? Further research about blackpowder development and weapons suggests that the quality of the powder factors heavily and modern gunpowder suggests "about 30 rounds of .45 caliber per pound" (one pound = 7000 grains and a typical .45 load ≅ 233 grains.)

Most 16th–18th century long rifles and pistols had a median caliber of .50, making the .45 is a good measure for abstraction. If modern powder translates to Best Quality then 60 rounds per "small keg." Reduce by 10 for Good, 20 for Common, and 30 for Poor qualities, or 50, 40, and 30 rounds, respectively.

The cost then is a based on the quality scale with 3s per shot with Common quality gunpowder, or 3x40, 120s (6gc), 450s (20gc) for Good Quality, and 1800s (90gc) for Best Quality.

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Good answer! Can anyone top it? – kelvingreen Feb 26 '14 at 13:58