Magazine (firearms) in the context of "Semi-automatic pistol"

On December 14, 2012, a mass shooting occurred at Sandy Hook Elementary School in Newtown, Connecticut, United States. The perpetrator, 20-year-old Adam Lanza, shot and killed 26 people. The victims were 20 children between six and seven years old, and six adult staff members. Earlier that day, before driving to the school, Lanza fatally shot his mother at their Newtown home. As first responders arrived at the school, Lanza killed himself with a gunshot to the head.

The incident is the deadliest mass shooting in Connecticut history and the deadliest at an elementary school in U.S. history. The shooting prompted renewed debate about gun control in the United States, including proposals to make the background check system universal, and for new federal and state gun legislation banning the sale and manufacture of certain types of semi-automatic firearms and magazines which can hold more than ten rounds of ammunition.

An assault rifle is a select fire rifle that uses an intermediate-rifle cartridge and a detachable magazine. Assault rifles were first put into mass production and accepted into widespread service during World War II. The first assault rifle to see major usage was the German StG 44, a development of the earlier Mkb 42. While immediately after World War II, NATO countries were equipped with battle rifles, the development of the M16 rifle during the Vietnam War prompted the adoption of assault rifles by the rest of NATO. By the end of the 20th century, assault rifles had become the standard weapon in most of the world's armies, replacing full-powered rifles and submachine guns in most roles. The two most successful modern assault rifles are the AK-47 and the M16 designs and their derivatives.

A submachine gun (SMG) or sub-gun is a magazine-fed automatic carbine designed to fire handgun cartridges. The term "submachine gun" was coined by John T. Thompson, the inventor of the Thompson submachine gun, to describe its design concept as an automatic firearm with notably less firepower than a machine gun (hence the prefix "sub-"). As a machine gun must fire rifle cartridges to be classified as such, submachine guns are not considered machine guns.

In the 20th century, the submachine gun was developed during World War I (1914–1918) as a close quarter offensive weapon, mainly for trench raiding. At its peak during World War II (1939–1945), millions of submachine guns were made for assault troops and auxiliaries whose doctrines emphasized close-quarter suppressive fire. New submachine gun designs appeared frequently during the Cold War, especially among special forces, commandos and mechanized infantrymen. Submachine gun usage for frontline combat decreased in the 1980s and 1990s.

An autocannon, automatic cannon, machine cannon or anti-tank machine gun, is a fully automatic gun that is capable of rapid-firing large-caliber (20 mm/0.79 in or more) armour-piercing, explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bullets) fired by a machine gun. Autocannons have a longer effective range and greater terminal performance than machine guns, due to the use of larger/heavier munitions (most often in the range of 20–60 mm (0.79–2.36 in), but bigger calibers also exist), but are usually smaller than tank guns, howitzers, field guns, or other artillery. When used on its own, the word "autocannon" typically indicates a non-rotary weapon with a single barrel. When multiple rotating barrels are involved, such a weapon is referred to as a "rotary autocannon" or "rotary cannon". If it uses a single barrel with a rotating cylinder with multiple chambers, it is known as a "revolver autocannon" or "revolver cannon"; both of these systems are commonly used as aircraft guns and anti-aircraft guns.

Autocannons are heavy weapons that are unsuitable for use by infantry. Due to the heavy weight and recoil, they are typically installed on fixed mounts, wheeled carriages, ground combat vehicles, aircraft, or watercraft, and are almost always crew-served, or even remote-operated with automatic target recognition/acquisition (e.g. sentry guns and naval CIWS). As such, ammunition is typically fed from a belt system to reduce reloading pauses or for a faster rate of fire, but magazines remain an option. Common types of ammunition, among a wide variety, include HEIAP, HEDP and more specialised armour-piercing (AP) munitions, mainly composite rigid (APCR) and discarding sabot (APDS) rounds.

A repeating rifle is a single-barreled rifle capable of repeated discharges between each ammunition reload. This is typically achieved by having multiple cartridges stored in a magazine (within or attached to the rifle) and then fed individually into the chamber by a reciprocating bolt, via either a manual or automatic action mechanism, while the act of chambering the round typically also recocks the hammer/striker for the following shot. In common usage, the term "repeating rifle" most often refers specifically to manual repeating rifles (e.g. lever-action, pump-action, bolt-action, etc.), as opposed to self-loading rifles, which use the recoil, gas, or blowback of the previous shot to cycle the action and load the next round, even though all self-loading firearms are technically a subcategory of repeating firearms.

Repeating rifles were a significant advance over the preceding single-shot, breechloading rifles when used for military combat, as they allowed a much greater rate of fire. The repeating Henry rifle was used by the infantry and Spencer rifle was used by the cavalry during the American Civil War and the subsequent American Indian Wars, and the first repeating air rifle to see military service was the Windbüchse rifle.

The Lee–Enfield (Enfield rifle) is a bolt-action, magazine-fed repeating rifle that served as the main firearm of the military forces of the British Empire and Commonwealth during the first half of the 20th century, and was the standard service rifle of the British Armed Forces from its official adoption in 1895 until 1957.

A redesign of the Lee–Metford (adopted by the British Army in 1888), the Lee–Enfield superseded it and the earlier Martini–Henry and Martini–Enfield rifles. It featured a ten-round box magazine which was loaded with the .303 British cartridge manually from the top, either one round at a time or by means of five-round chargers. The Lee–Enfield was the standard-issue weapon to rifle companies of the British Army, colonial armies (such as India and parts of Africa), and other Commonwealth nations in both the First and Second World Wars (such as Australia, New Zealand, South Africa, and Canada). Although officially replaced in the United Kingdom with the L1A1 SLR in 1957, it remained in widespread British service until the early/mid-1960s and the 7.62 mm L42A1 sniper variant remained in service until the 1990s. As a standard-issue infantry rifle, it is still found in service in the armed forces of some Commonwealth nations, notably with the Bangladesh Police, which makes it the second longest-serving military bolt-action rifle still in official service, after the Mosin–Nagant (Mosin-Nagant receivers are used in the Finnish 7.62 Tkiv 85). Total production of all Lee–Enfields is estimated at over 17 million rifles.

The Henry repeating rifle is a lever-action tubular magazine rifle. It is famous for having been used at the Battle of the Little Bighorn and having been the basis for the iconic Winchester rifle of the American Wild West.

Designed and introduced by Benjamin Tyler Henry in 1860, the original Henry was a sixteen-shot .44 caliber rimfire breech-loading lever-action rifle. It was produced from 1860 until 1866 in the United States by the New Haven Arms Company. The Henry was adopted in small quantities by the Union in the American Civil War, favored for its greater firepower than the standard-issue carbine. Many later found their way West, notably in the hands of a few of the Sioux and Cheyenne in their defeat of George Armstrong Custer's U.S. Cavalry troops in June 1876.

A repeating firearm or repeater is any firearm (either a handgun or long gun) that is designed for multiple, repeated firings before the gun has to be reloaded with new ammunition.

Unlike single-shot firearms, which can only hold and fire a single round of ammunition, a repeating firearm can store multiple cartridges inside a magazine (as in pistols, rifles, or shotguns), a cylinder (as in revolvers), or a belt (as in machine guns), and uses a moving action to manipulate each cartridge into and out of the battery position (within the chamber and in alignment with the bore). This allows the weapon to be discharged repeatedly in relatively quick succession, before manually reloading the ammunition is needed.

Tracer ammunition, or tracers, are bullets or cannon-caliber projectiles that are built with a small pyrotechnic charge in their base. When fired, the pyrotechnic composition is ignited by the burning powder and burns very brightly, making the projectile trajectory visible to the naked eye during daylight, and very bright during nighttime firing. This allows the shooter to visually trace the trajectory of the projectile and thus make necessary ballistic corrections, without having to confirm projectile impacts and without even using the sights of the weapon. Tracer fire can also be used as a marking tool to signal other shooters to concentrate their fire on a particular target during battle.

When used, tracers are usually loaded as every fifth round in machine gun belts, referred to as four-to-one tracer. Platoon and squad leaders will load some tracer rounds in their magazine or even use solely tracers to mark targets for their soldiers to fire on. Tracers are also sometimes placed two or three rounds from the bottom of magazines to alert shooters that their weapons are almost empty. During World War II, aircraft with fixed machine guns or cannons mounted would sometimes have a series of tracer rounds added near the end of the ammunition belts, to alert the pilot that he was almost out of ammunition. However, this practice similarly alerted astute enemies that their foes were nearly out of ammunition. More often, however, the entire magazine was loaded four-to-one, on both fixed offensive and flexible defensive guns, to help mitigate the difficulties of aerial gunnery. Tracers were very common on most WWII aircraft, except for night fighters, which needed to be able to attack and shoot down the enemy before they realized they were under attack, and without betraying their own location to the enemy defensive gunners. The United States relied heavily on tracer ammunition for the defensive Browning M2 .50 caliber machine guns on its heavy bombers such as the B-24 Liberator.