By Anthony Mitchell
Introduction
In this article we will have a brief look at what makes a gun go bang: propellants (or powder) and the primers.
Propellants
Broadly speaking, there are two main types of powder, black powder (or gunpowder) and smokeless powder.
Black Powder has been around for centuries. It is a mixture of saltpetre, charcoal and sulphur. It is bulky, generates a lot of smoke when fired, and leaves a lot of carbon fouling in the barrel after firing.
Smokeless Powder was developed in the 19th century. It was less bulky than black powder and could propel a bullet at much higher velocity. Also, the amount of fouling was greatly reduced.
Primers
When struck by the gun’s firing pin, the priming compound ignites the powder charge. In a centrefire cartridge the primer is located centrally in the base of the cartridge, whereas in the rim fire cartridge, the priming compound is located in the cartridge rim.
Corrosive vs Non-Corrosive Priming
As we have seen earlier, smokeless powder had many advantages over black powder. However, after smokeless powder came into use, it was noticed that gun barrels were wearing out more rapidly than before. Initially, smokeless powder was thought to be the culprit. However, the priming compound was found to be the problem. A by-product remaining in gun barrels was found to be a chemical similar to common table salt. And just like table salt, it attracted moisture, which started rust.
When black powder was the propellant, the carbon fouling tended to protect the barrel to a certain extent. This meant that guns had to be cleaned rigorously to prevent premature barrel wear. A common method used previously involved pouring boiling water down the barrel to remove any salt. Cleaning solvents were also developed specifically for corrosive ammunition.
Nowadays, virtually all modern ammunition has non-corrosive priming. The exception may be old military surplus ammunition, especially from the Communist Bloc.
Summary
Modern ammunition is inherently reliable, clean and accurate. Modern barrel steels combined with modern cleaners and lubricants can mean that the life of a gun barrel is generally pretty long. In the case of a .22LR firearm, the barrel will generally wear out before it will rust out.
Until next time, have a happy and safe shoot!