The humble tube of brass, the cartridge case. It holds the components of the cartridge together, bullet, powder and primer. It is the primary agent of obturation, a military centric term for sealing against the leakage of high-pressure gases. As the powder is lit from the primer and the pressure builds the brass case expands sealing the chamber. It then collapses allowing for extraction. In semi-auto firearms the extracted brass carries away heat thus contributing to the cooling of the gun. This cooling is present in most firearms except for maybe revolvers as they retain the case.
What are Bullet Casings (Cartridges) Made Of?
The cases made in the US are mostly brass. But a lot of European ammo uses steel cases. Brass is considered a strategic resource and steel is more readily available, cheaper and gets the job done, however it is not considered reloadable. Aluminum has been flirted with but again is a single use item, not readily adaptable to reloading.
Berdan VS Boxer Primers
Berdan primed case, common again in European and most Asian manufactured ammo is not readily or easily reloadable, as the primer pocket has two vents and the primer’s anvil is part of the case. In the US and much of the higher quality imports, boxer primed cases are the norm with a single centrally placed vent for easy de-capping and integral anvil in the primer. This arrangement allows for easy reloading and is relatively straight forward.
Rimmed or Flanged VS Rimless Cartridge Magazine
The flat lip extending above the diameter of the case indicates a rimmed case. The Brits refer to them as ‘flanged’. Cartridges like the 30-30, 357 Magnum, 44 Magnum and the 45 Colt are rimmed cartridges. Rimmed cartridges are used in tube magazine equipped lever actions and most revolver cartridges. The old English double were also equipped to shoot flanged cartridges. They assured easy extraction for quick reloading, desirable when facing a ticked of pachyderm. Rounds like the 308 Winchester, 223 Remington and the 270 Winchester are what is called rimless cartridges. They have an extraction groove but the rim is the same diameter as the case base. Ever seen the humungous 50 AE loaded for the Israeli made Desert Eagle. This fat case has the rim smaller than the case; it is the same diameter of the 44 Remington Magnum and is referred to as a “rebaited” rimmed cartridge. Others similar configurations are the 450 Bushmaster for the AR rifle with the same rim diameter as the 5.56 NATO round. The 38 Super Automatic is a semi-rimmed cartridge, with a slight rim. This cartridge was originally made specifically for the Mexican market. Mexico prohibited civilians owning any weapon chambered in any of the military calibers. Colt came out with the 38 Super Auto, as 9mm Luger and 45 ACP where verboten.
The last of the cartridge case rim designs that is common is the belted rim. The cartridge has a belt and rim of a larger diameter than the case a gives a unique appearance. First available in the 375 H&H Magnum it became the hallmark of magnum rifle cartridges. This trend is fading as a lot of the newer rounds introduced lately are rimless designs, like the 338 Lapua Magnum, the darling of the long-range sniping community. The hunters of dangerous game like the smooth feeding of the rimless design over the belted designs.
Custom Shooting Ranges Made in the USA
Most auto-pistol rounds are rimless, while most revolver rounds are rimmed. Rimmed rifle rounds for the bolt guns are the Russian 7.62 x 54Rmm, the 30-40 Krag and the British 303. The humble brass tube comes in varying configurations from straight sides, tapered and bottlenecked. Without it we could not enjoy the shooting performance for fun, competition, self-defense and hunting. From the lowly 22 Long Rifle to the mighty 50 BMG we have the fantastic cartridge all in a brass tube. Shooting Range Industries builds custom shooting ranges for your practice and training. Contact us to learn more today!