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Firearm Cartridges Part 3; Smokeless Powder, BAR Firearms, Maxim Machine Guns & More

During the turn of the century military and sporting ammunition was switching from black powder to nitrated cellulose or more commonly known as smokeless power. Smokeless powder is a bit of a misnomer as there is some smoke but compared to the cloud put out by black powder it is relatively smokeless. With more potential energy smokeless propellants pushed the projectile at much higher velocities than black powder was capable of doing.

Smokeless Powder Cartridges

On the military front there was an international push switch to smokeless military propellants in the 19th and early 20th centuries. Germans had the advantage of Paul Mauser’s bolt action rifle Gew 88 (short for Gewehr German for rifle) and the 7.9 x 57mm cartridge, better known as the 8mm Mauser in the US. The trend was towards bolt action guns. The 8mm Mauser was the basis to the 7mm but German cartridges introduced the spitzer bullet, German for pointed. Most military’s while adopting smokeless propellants the moribund decision was to adopt bullets with the traditional round nose projectiles. But the German spitzer was more aerodynamic, creating a longer and flatter trajectory, a major tactical innovation the stymied the British in the Boer War and the Americans in the Spanish American War. The belligerents, the Boer and Spanish forces were equipped with the 7 x 57mm Spanish Mauser, the little brother of the 8mm Mauser. Both sported the spitzer bullet and created a tactical advantage in flatter trajectories, longer range and better accuracy. The 8mm Mauser was the progenitor of the US 30-06 and influenced the design of many sporting rounds. Even the British .303 and the Russian 7.62 x 54R (R is rimmed) though rimmed were in the same performance category as the 8mm Mauser.

Cartridge Nomenclature

A note on cartridge nomenclature: there are rimmed, semi-rimmed, rimless, rebaited and belted. Cartridges can also be straight sided, tapered sided or bottle neck. Substitute flanged for rimmed and you have the British nomenclature. In the black powder era most cases were rimmed straight sided cartridges or bottle necked, reducing the cartridge diameter down to bullet diameter.

Maxim Machine Guns

The 8mm and subsequent copies made full-automatic arms, i.e. machine guns practical. The Gatling with multiple breech loading barrels could overcome the black powder fouling being externally powered by a crank. But the fouling would render a recoil or gas operated machine gun inoperative in short order. The Maxim machine gun ruled the battlefield during the early twentieth century wars. The Maxim and the British Vicker were modified Maxims, were water cooled and were reliable with extended fire endurance and belt fed.

Air & Cartridge Cooled Auto Rifles

Air cooled machine guns depend on not only air but the cartridge to cool the gun. Auto rifles like the US BAR and modern assault weapons are air and cartridge cooled. Understand that a firearm is a heat engine. When fired that heat is transferred to the breech and cartridge. On extraction the cartridge pulls heat from the breech and removes it. Rapid fire cartridge extraction contributes to the cooling of the gun. Another consideration of the cartridge refers to obturation, the sealing of the breech. As the cartridge expands on firing it seals the chamber and prevents gases from exiting the breech or chamber into the shooters face. This obturation is a major obstacle in developing caseless ammunition.

Rimless Bottleneck Cartridge

In effect the German innovations of a rimless, bottleneck cartridge with a tapered aerodynamic projectile has defined modern ammunition. Round nosed bullets are still with us and are used for hunting in brush or forested environments at short to medium ranges, about 150 to 200 yards or meters. Most consider the round nosed bullet less prone to deflection in brush. Paul Mauser should have thanks of anyone engaging man or beast for his cartridge innovations, a legacy that lives on.

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