What is the Effective Combustion Volume or Free Case Capacity?

The Effective Combustion Chamber Volume is found by subtracting the bullet portion inside the case from the Case Capacity, which is available in our cartridge database and safety standards.

Important: Actual case volume can vary greatly. We recommend measuring your cartridges before loading.

To measure case volume: weigh a dry empty case (with primer), fill it with water, removing air bubbles, fill to the case neck, then weigh again. Subtract the dry weight from the filled weight to get capacity in grains of water, the standard unit used in our database.

Bullet volume inside the case depends on the bullet type. For flat-base bullets, use diameter and seating depth. For boattail or hollow-base bullets, consider the base design.