Load density is a calculation of case capacity versus powder bulk density. Case capacity is measured by taking a piece of firedbrass, filling it up with water and then loading a bullet into the case neck at the tested OACL listed in Nosler’s Reloading Guide #7. The weight of water left in the brass after the bullet has been seated is the case capacity. Powder bulk density is how many grams of a particular powder fit into one liter.
In Nosler’s Reloading Guide #7, a 270 WSM case holds 73 grains of water (case capacity) loaded with our 130 grain bullets. It also states that the maximum charge of MAGPRO is 72 grains in this cartridge. Incidentally, MAGPRO has a powder bulk density of .970 grams per cubic centimeter so the load density calculation looks like this:
Powder Charge (72 grains) ÷ [Case Capacity (73 grains) x Powder Bulk Density (.970)] = 102% Load Density.