JS
Dont have a formula but... You will not find an easier to use or more versitile program than the new RCBS Load program. They have a cartridge designer program that is great. In this program you start with the drawing of a basic cartridge and then modify it to your desires. Seat a bullet 0.001" deep and you have usable capacity in water. It is very useful for the money. there are "better" programs available but they are much more expensive.