For those interested, here is some information on historic and a modern load for a King’s Pattern Brown Bess and a modern Brown Bess Reproduction.
Historic Powder Charges from Dr. De Witt Bailey’s published works and other original documentation.
Note: The pan was primed from the cartridge, so not all the powder went down the bore.
1. Seven Years War (French and Indian War in North America) Powder Charge of 165 grains of “Musket” Powder, which was probably 1Fg.
2. American Revolutionary War. Generally increased to 190 grains and in some cases up to 220 grains. Note: There was a huge scandal about the powder supplied to British Forces from England during this War. This scandal had to do with both the quantity of powder in the kegs, as many were found with sand or a combination of sand and stones in the powder, and also poor quality powder in many other cases.
3. By the first quarter of the 19th century, there had been significant increases in the quality of black powder, so the charge was reduced to 135 grains of Musket Powder.
The weight of the bullets used in the Brown Bess during the 18th century was also important. Though the caliber always given was supposed to be .69 Caliber, unfired balls that were excavated from British Sites in different places in North America actually show the more common sizes of the balls were .70 and .71 Caliber rather than .69 Caliber, according to the findings published by T.M. Hamilton in the book “Colonial Frontier Guns.”
Grain weight of Ball Sizes used in the Brown Bess during the 18th century.
A weight of 495 grains for a round ball made of Pure Lead with a diameter of .69".
A weight of 517 grains for a round ball made of Pure Lead with a diameter of .70".
A weight of 539 grains for a round ball made of Pure Lead with a diameter of .71".
But powder charges and weight of the different ball sizes were not the entire story. The balls were wrapped in linen cartridge paper, so there probably was some small gas leakage from that. During the 18th century, actual Musket Bore Sizes generally ran .76 caliber to .78 caliber and a small percentage as high as .80 caliber. What makes that important was the larger the bore diameter, the more gas leakage and thus less pressure in the bore.
Modern Brown Bess Replica Bore sizes run smaller than the Original Bore Sizes, often right around .75 caliber and in some cases some bores have been reported as small as .729.
For example, the Bore Size in my Pedersoli Brown Bess Carbine was either .751” or .753.” (My apology, but the last time I competed with that Musket was in 1979 and I sold that gun in the early 2000’s, so my memory is a bit fuzzy as to which was the actual size.) I used a .735” ball weighing approximately 598 grains with a greased, heavy pillow ticking patch that was so tight in the bore, I had to use a large short starter. (This larger diameter/heavier ball and tighter patch combination would have not allowed as much gas leakage as the linen cartridge paper wrapped smaller diameter balls in the historic period.) My target/accuracy load was 70 grains of 2 Fg and the 2 Fg probably gave higher pressures than the older 1Fg used in the early 19th century.
Of course, no one can accurately test the pressure in the bore of the original 18th and early 19th century loads, because of the differences in original ball and bore sizes and of course the powder and cartridge paper are not the same. I also was never able to test the pressure in the bore with my load in my modern Pedersoli Brown Bess Carbine. However, I suspect that with the tighter ball and patch, smaller bore size and finer grained powder; my modern load may have come closer to the pressure in original Military Muskets and loads than one may suspect ”“ though maybe not quite as high of pressure as the original loads. I do know that ball/patch combination with the 70 grain charge of 2Fg was more accurate than a larger charge of powder.
Gus
