KK;
Thanks for the compliment, but this info all came from others. The industry standard for Black Powder measures was given some yrs back in the American Rifleman, back when they had a lot of great info. It was reprinted in their first Handloaders Guide (may be their last one, not sure) & I kept it. The shot volume came from older Hercules/Alliant handloader guides where for years they showed the length of a 1oz shot column in the standard bores of 10, 12, 16, 20 & 28 Gauges as well as the .410 bore. It was a simplr matter to calculate from the dia & length what the CuIn's would be & they all hoovered around that .288 which was virtually identical to the 2˝ dram BP volume.