Richard Atkins gives an insight into the powder that makes our cartridges go bang!

B

lack powder, commonly called ‘gunpowder’, served the armies and navies of the world and later also the sportsman as handheld firearms developed.

Black powder had one problem – smoke! Battlefield commanders were unable to see the enemy once the first heavy bombardments had been fired. Black powder is messy, fouling gun barrel bores, and the residues are prone to cause rusting.

It wasn’t until the mid-1800s that French chemist Henri Braconnot took the first steps towards ‘smokeless’ powders. Braconnot treated fibrous cellulose with nitric acid to produce an explosive polymer. The early products were difficult to handle safely, but by the 1880 the first safe nitrocellulosebased propellants were being used.

Smokeless powder

Early smokeless powders from the 1880s onward met with varying responses from shooters. The lack of thick smoke and much reduced fouling were greatly appreciated. But some shooters felt smokeless powders were less consistent, some they were too weak, while others said they might be too strong! There were occasional mishaps, too.

Cartridges were hand loaded for customers by an apprentice working at the back of a gun shop. Some used an early loading machine, such as the patented Erskine wooden tray type. This measured the powder by volume, not weight, just as with black powder. For this reason early smokeless powders were made as ‘bulk’ powders, so that their volume compared safely with black powder equivalents.

However that obscured the advantages of nitrocellulose powders – they could produce the same amount of energy in charges of lower volume and weight. Less bulky powders were developed, allowing for a longer wad column in the same length of case. Many 12 gauge sporting guns were chambered for 2½ in cartridges and the 2 in lightweight game gun was also popular.

Two famous powders of that time, Amberite and later Smokeless Diamond, carried on their advertisements their respective charge weights of 42 grains and 33 grains respectively. Even the Smokeless Diamond’s 33 grains is typically much higher than the smokeless powders we use today, thanks to much improved manufacturing processes, refined coatings and additives and greater choice of controlling burning rates. Incidentally, the correct term for propellant powders ‘burning’ is actually ‘deflagrate’ – but I’ll stick with ‘burning’ here as it’s more widely used and understood.