Editing Firearm (section)

===Composition of the modern round/cartridge===

*Casing - The metal jacket that houses the propellant, primer, and to an extent the bullet (pardoning telescopic munitions which house the bullet completely.) Usually made from brass, they can be made from steel or plastics (at the detriment of the gun itself, unless designed for such).

*Propellant - Powder that is used to propel the bullet/slug/projectile. In the good ol' days, it used black powder (which was made from charcoal, sulphur, and saltpeter - either potassium nitrate or sodium nitrate), but those clouded the air with black smoke, left soot in the gun, were corrosive, and weren't powerful. Most modern rounds use a double base powder (generally guncotton/nitrocellulose, both dry and in a dissolved form called collodion, and nitroglycerin), may include a variety of stabilizers (to improve shelf life of the round) and deterrents (to prevent the cartridge from being too "hot" and prematurely combusting or shattering the barrel from overpressure). Historically, the British formed their propellant as stiff string called Cordite stuffed into cartridges before the mainstream use of small grains took over. For artillery, they make good use of triple base propellants, which is smokey as hell but burn well with no corrosive fouling.

*Primer - What activates the powder in the rounds themselves. Replacing the finnicky and hydrophobic matchlock, wheellock, and flintlock, they're percussion caps filled with sensitive explosive compounds (like picrates, fulminates, perchlorates, styphnates, tetrazenes, or azides) that ignite upon being hit. Generally a firm dent is enough to activate the munitions. Modern commercial ammo generally use non-corrosive compression sensitive materials, though many governments kept using corrosive primers well into the Cold War due to surplus stock and cost reduction.

*Bullets - What people get tripped up on in naming munitions. Being the projectile, anyone loading the munitions has a vast choice of what can be used as a bullet. Generally, lead, steel, and tungsten make the core of the round (thanks to their weight) while the outer coat for the round could be lead (since it is also very malleable), copper, and nickel, though Teflon and certain plastics can also be used. If you're feeling lucky, you can load a variety of other materials into the rounds (or shells for shotguns). Take for example salt, which doesn't kill, but you can mark people and they sting like hell. Alternatively, if you're riot police trying to suppress a crowd without killing them, you'd use bullets or shotgun shells loaded with rubber, foam, wax, plastic, bean bag rounds, or tear gas with reduced propellant. If it hits you in the head or in an unlucky spot, you might die from blunt force trauma but it's less lethal than an actual bullet.