Gooddaytoya!
40 Cal
Instead of going through all the algebra and conversions to figure the weight of a specific size pure lead round ball, you can use a constant x diameter cubed. So, a 395 caliber lead ball weight equals the constant 1502.6 x .395 x .395 x ..395 = 92.6 grains. Much easier. I thought this might be helpful to some of you guys.