Reloading 9mm

Reloading 9mm: "It is very important that the reloader understands the relationship between mass and volume. As the charge weight increases, the load density increases, so there is less airspace. Either factor alone would raise pressure significantly. Obviously, more powder generates more energy, raising pressure. Less obvious is that more powder occupies more space, which also raises pressure, as the expanding gases have less available volume. However, these factors cannot be isolated, and 9mm has a relatively small case. It is extremely important to work up loads properly and safely with 9mm. Certain fast burning powders can cause dangerous pressures with extremely small increases in charge weight."