Firearm propellants have progressed from black powder to semi-smokeless to smokeless powders. Smokeless powders are not truly smokeless as some combustion with take place outside the barrel and incomplete burning will produce some smoke.
Traditional Black Powder
Black powder is a mixture of charcoal (willow is the best), sulfur and potassium nitrate also known a saltpeter. Petre, is Latin for salts. Sulfur is a catalyst, charcoal the fuel and potassium nitrate is the oxidizer. Some of the black powder burns, the rest is particulates that exit the barrel as smoke or are deposited in the bore as fouling. The bore deposits are hydroscopic and absorb water from the air and are very corrosive if left in the bore. Muzzle loader were good for about 20 shots before they were befouled enough to need cleaning, not a good expedient faced on the battlefield in a martial contest.
Semi Smokeless & Smokeless Powders Burn Rate
Semi-smokeless and smokeless powders are nitrated cellulose. The British came up with strands of cordite that were manually loaded into cartridges, before the fixing of the bullet into the case. Today we have a plethora of powders. Grain shape determines some burning characteristics. Flake, flattened ball and ball shaped powders burn from the outside in, with progressively less gas production as the surface area shrinks. Tubular powders are like short pasta with a hole in the center of an elongated grain. These burn from the outside in and from the inside out producing a relatively uniform gas production. The hot gases produced by the burning of the powders expand, build pressure and force the projectile from the barrel. Graphite is a common coating to lubricate the grain and reduce static electrical charges. Other coatings are used to regulate the burning characteristics of the powder as well.
Single, Double & Triple Based Propellants
The caloric content of the powder can be improved. Single-base powders used in sidearm and shotgun ammo are usually single base powders consisting only of nitrate cellulose. Double-base powders found in rifle propellants add a dash of nitroglycerin to spice up the power. Some large bore military applications use a triple-base powder. Nitroguanidine was the third leg of the triple-based powders, and dates to the 1930’s. This is expensive and has not migrated down to the personal firearms level. Modern propellants have improved many cartridges. Some of the smaller hauls like the .308 Winchester can hold their own compared to the 30-06 up to about 165-grain bullets, over that the larger case can push the heavier bullets much better.
Additives are used to tame the powder. Deterrents to slow the burning rate, stabilizers to prevent or slow down self-decomposition. De-coppering additives to slow the build up of copper fouling from the bullet jackets. Flash reducers to minimize the brightness of the muzzle flash, now these produce more smoke. Wear reduction additive to protect against barrel erosion and wear. Rosin is sometimes added to maintain the shape of the grain.
Custom Shooting Ranges for Firearms Training & Practice
As can be seen propellants are a brew of various chemicals to achieve certain characteristics. The ammunition loader or the hobby reloader can produce some very good and sophisticated ammunition products for the consumer, sportsmen and the military. Shooting Range Industries designs and builds custom shooting ranges that are modular and portable with a host of impressive accessories. Contact us to learn more today!