The one x-ray that I have seen with a recovered, military musket, still loaded with buck-n-ball, has the buckshot on the powder, with a small separation, followed by the ball, so when I've loaded this into a cartridge, I add an extra loop or two of string between the buckshot and the ball. I pour in the powder, then invert the cartridge, and load. Seem to add extra hits on targets simulating a line of advancing soldiers, and sometimes gives me extra hits on a single target. I've not had buckshot alone strike the target I'm aiming at, when loaded with buck-n-ball.
LD