Originally Posted by Doc Hoy
A projectile made of pure lead will have a specific weight. I worked out the weights of pure lead balls of various diameters a while back but I have lost the calculations and can't remember what they are. Since you can't trust that a .454 mold will produce a consistent .454 ball, I worked out the calculations for every thing from a .451 to a .459. The calculations are quite simple but they are tedious. I wish I still had them, because when I worked them up, I remember comparing them with the projectile weights from the Lyman Handbook and found that the Lyman book published weights that were slightly less than my calculations for pure lead in every case. This means that the Lyman bullets were likely not pure IF THEY ACTUALLY WEIGHED THE BULLETS. And I think they did.
I calculate the theoretical weight of a lead round ball by cubing its diameter and then multiplying by 1503 to get the weight in grains.
Example: A .50 round ball. .5 X .5 X .5 = .125 .125 X 1503 = 187.875
Don't take the last couple of decimal points too seriously, my 1503 constant is rounded off to the nearest whole number and unless you have a micrometer that measures ≤ .0001", is accurate enough.
The colors on a lead ingot are most likely from a microscopic thin layer of lead oxide on the surface. The color depends on the thickness of this microscopic thin layer. It's an interference phenomenon same as the colors in soap bubbles or a thin layer of spilled oil on water.