Propellant powders: the reloader’s fuel
PROPELLANT powder is a mixture of chemicals containing stored energy. Smokeless powders are safer to handle and use than older propellant types. Progressive burning characteristics adapt them to modern firearms. High pressures and high velocity are obtainable within certain parameters.
The energy source is either nitro-cellulose or both nitro-glycerin and nitrocellulose. If made of nitrocellulose alone, the powder is known as single-base. If made of both energy sources, it is known as double-base. Burning rates are controlled by granule (or kernel) size and a deterrent coating. A final coating of graphite is applied to facilitate flow in measuring, and reduce static electricity.
Three basic types are made for sporting ammunition: flake, extruded and ball. Flake and extruded granules are extruded, perforated, and cut to exact length. The majority of extruded powders are more commonly known as “stick” powders.
Before World War II, the one American smokeless powder company was Du Pont, which made a line of single-base IMR (Improved Military Rifle) powders. Du
