magazine

Nomenclature

With the increased use of semi-automatic and automatic firearms, the detachable magazine became increasingly common. Soon after the adoption of the M1911 pistol, the term "magazine" was settled on by the military and firearms experts. Although the term "clip" is often used to refer to detachable (never fixed) magazines, this usage remains a point of strong contention. The defining difference between a clip and a magazine is the presence of a feed mechanism, typically a spring-loaded follower, which a clip lacks.

History

The earliest firearms were loaded with powder and a lead ball in paper, and to fire more than a single shot without reloading required multiple barrels, such as in pepper-box guns, double-barreled rifles, double-barreled shotguns, or multiple chambers, such as in revolvers. The main problem with these solutions is that they increase the bulk and/or weight of a firearm, over a firearm with a single barrel and/or single chamber. However, many attempts were made to get multiple shots from loading a single barrel through the use of superposed loads. While some early repeaters such as the Kalthoff repeater operated using complex systems with multiple feed sources for ball, powder, and primer, easily mass-produced repeating mechanisms did not appear until self-contained cartridges were developed in the 19th century.

Early tubular magazines

The first successful mass-produced repeating weapon to use a "tubular magazine" permanently mounted to the weapon was the Austrian Army's Girardoni air rifle, first produced in 1779.

The first mass-produced repeating firearm was the Volcanic Rifle which used a hollow bullet with the base filled with powder and primer fed into the chamber from a tube called a "magazine" with an integral spring to push the cartridges in to the action, thence to be loaded into the chamber and fired. It was named after a building or room used to store ammunition. The anemic power of the Rocket Ball ammunition used in the Volcanic doomed it to limited popularity..

The Henry repeating rifle is a lever-action, breech-loading, tubular magazine-fed repeating rifle, and was an improved version of the earlier Volcanic rifle. Designed by Benjamin Tyler Henry in 1860, it was one of the first firearms to use self-contained metallic cartridges. The Henry was introduced in 1860 and was in production until 1866 in the United States by the New Haven Arms Company. It was adopted in small quantities by the Union Army in the American Civil War and was favored for its greater firepower than the standard issue carbine. Many later found their way Westward and was famed both for its use at the Battle of the Little Bighorn, and being the basis for the iconic Winchester lever-action repeating rifle, which is still in production to the present day. The Henry and Winchester rifles would go on to see service with a number of militaries including Turkey. Switzerland and Italy adopted similar designs.

The second magazine-fed firearm to achieve widespread success was the Spencer repeating rifle, which was designed by Christopher Miner Spencer in 1860, also saw military service during the American Civil War. The Spencer used a tubular magazine located in the butt of the gun instead of under the barrel and it used rimfire metallic cartridges. The Spencer was successful, but the rimfire ammunition did occasionally ignite in the magazine tube and destroy the magazine. It could also injure or kill the user.

The new bolt-action rifles began to gain favor with militaries in the mid-1880s and were often equipped with tubular magazines. The Mauser Model 1871 was originally a single-shot action that added a tubular magazine in its 1884 update. The Norwegian Jarmann M1884 was adopted in 1884 and also used a tubular magazine. The French Lebel Model 1886 rifle also used 8-round tubular magazine.

Integral box magazines

The military cartridge was evolving as the magazine rifle evolved. Cartridges evolved from large-bores (.40 caliber/10 mm and larger) to smaller bores that fired lighter, higher-velocity bullets and incorporated new smokeless propellants. The Lebel Model 1886 rifle was the first rifle and cartridge to be designed for use with smokeless powder and used an 8 mm wadcutter-shaped bullet that was drawn from a tubular magazine. This would later become a problem when the Lebel's ammunition was updated to use a more aerodynamic pointed bullet. Modifications had to be made to the centerfire case to prevent the spitzer point from igniting the primer of the next cartridge inline in the magazine through recoil or simply rough handling. This remains a concern with lever-action firearms today. It became apparent that the tubular magazine is generally unsuitable for storage of pointed bullet cartridges, and hence the need for a different magazine design.

Two early box magazine patents were the ones by Rollin White in 1855 and William Harding in 1859. A detachable box magazine was patented in 1864 by the American Robert Wilson, however, unlike later box magazines this magazine fed into a tube magazine and was located in the stock of the gun. Another box magazine, closer to the modern type, though non-detachable, was patented in Britain (No. 483) by Mowbray Walker, George Henry Money and Francis Little in 1867.

James Paris Lee patented a box magazine which held rounds stacked vertically in 1875, 1879 and 1882, and was first adopted by Austria in the form of an 11mm straight-pull bolt-action rifle, the Mannlicher M1886, possibly the first serially produced rifle with a box magazine. It also used a cartridge clip which held 5 rounds ready to load into the magazine.

The bolt-action Krag–Jørgensen rifle, designed in Norway in 1886, used a unique rotary magazine that was built into the receiver. Like Lee's box magazine, the rotary magazine held the rounds side-by-side, rather than end-to-end. Like most rotary magazines, it was loaded through a loading gate one round at a time, this one located on the side of the receiver. While reliable, the Krag–Jørgensen's magazine was expensive to produce and slow to reload. It was adopted by only three countries, Denmark in 1889, the United States in 1892, and Norway in 1894.

A clip (called a charger in the United Kingdom) is a device that is used to store multiple rounds of ammunition together as a unit, ready for insertion into the magazine or cylinder of a firearm. This speeds up the process of reloading the firearm as several rounds can be loaded at once, rather than one round being loaded at a time. Several different types of clips exist, most of which are made of inexpensive metal stampings that are designed to be disposable, though they are often re-used.

Detachable box magazines

Firearms using detachable magazines are made with an opening known as a magazine well into which the detachable magazine is inserted. The magazine well locks the magazine in position for feeding cartridges into the chamber of the firearm, and requires a device known as a magazine release to allow the magazine to be separated from the firearm.

The M1879 Remington–Lee was the first rifle with a successful detachable box magazine design. Its followup, the Lee–Metford rifle, developed in 1888, also has a detachable box magazine, and the spare one could be optionally worn on soldier equipment, although with the adoption of the Short Magazine Lee–Enfield Mk I this became only detachable for cleaning and not swapped to reload the weapon.

The first completely modern removable box magazine was patented in 1908 by Arthur Savage for the Savage Model 99 (1899), although it was not implemented on the 99 until 1965. James Paris Lee's patent of November 4, 1879, Number 221,328 would have been before Arthur Savage's magazine.

Lee's magazine was also used on the Remington Lee model 1899 factory sporting rifle. Other guns did not adopt all of its features until his patent expired in 1942: It has shoulders to retain cartridges when it is removed from the rifle. It operates reliably with cartridges of different lengths. It is insertable and removable at any time with any number of cartridges. These features allow the operator to reload the gun infrequently, carry magazines rather than loose cartridges, and to easily change the types of cartridges in the field. The magazine is assembled from inexpensive stamped sheet metal. It also includes a crucial safety feature for hunting dangerous game: when empty the follower stops the bolt from engaging the chamber, informing the operator that the gun is empty before any attempt to fire.

The first successful semi-automatic pistol was the Borchardt C-93 (1893) and incorporated detachable box magazines. Nearly all subsequent semiautomatic pistol designs adopted detachable box magazines.

The Swiss Army evaluated the Luger pistol using a detachable box magazine in 7.65×21mm Parabellum and adopted it in 1900 as its standard sidearm. The Luger pistol was accepted by the Imperial German Navy in 1904. This version is known as Pistole 04 (or P.04). In 1908 the German Army adopted the Luger to replace the Reichsrevolver in front-line service. The Pistole 08 (or P.08) was chambered in 9×19mm Parabellum. The P.08 was the usual side arm for German Army personnel in both World Wars.

Double-stack magazines

The earliest examples of double-stack, single-feed box magazine patents are by the Austro-Hungarian Karl Krnka in July 1888, and the English inventor Joseph James Speed of Waltham Cross in November 1888. The earliest double-feed examples are by the British George Vincent Fosbery in 1883 and 1884, Schweizerische Industries-Gesellschaft, better known as SIG Sauer, in March 1887, and Fritz von Stepski and Erich Sterzinger of Austria-Hungary in November 1888.

One of the earliest rifles with a double-stack staggered-feed magazine is the 1889 Schmidt-Rubin. James Paris Lee is sometimes claimed to have invented the double-stack, staggered-feed detachable box magazine but he did not design one until 1892 for the Mark II Lee-Metford, three years after the Schmidt-Rubin.

The first pistol with a double-stack, staggered-feed magazine was the Mauser C96 although it was an integral design fed by stripper clips and located in front of the grip rather than in the modern configuration of in the grip. A detachable, double-stack staggered-feed box magazine was used in the Bergmann Mars pistol, designed in 1903, but it too was in front of the grip rather than in it. The first detachable double-stack, single-feed magazine in the grip for pistols was probably the one patented by the American Elbert H. Searle in 1904 and adopted by Arthur Savage though he did not apply it in practice to his designs until much later.

During World War One, Schmeisser's Cone was invented in 1916 by Hugo Schmeisser which allowed high-capacity double-stack, single-feed box magazine using guns to function reliably although it wasn't implemented on any of his designs until after the war. The first reliable high-capacity double-stack, staggered-feed box magazine was developed by the American designer Oscar V. Payne for the Thompson submachine gun around the same time as Schmeisser's Cone.

Function and types

All cartridge-based single-barrel firearms designed to fire more than a single round of ammunition without manual reloading require some form of magazine designed to store and feed cartridges into the firearm's action. Magazines come in many shapes and sizes, with the most common type in modern firearms being the detachable box type. Most magazines designed for use with a reciprocating bolt firearm (tube fed firearms being the exception) make use of a set of feed lips which stop the vertical motion of the cartridges out of the magazine but allow one cartridge at a time to be pushed forward (stripped) out of the feed lips by the firearm's bolt into the chamber. Some form of spring and follower combination is almost always used to feed cartridges to the lips which can be located either in the magazine (most removable box magazines) or built into the firearm (fixed box magazines). There are also two distinct styles to feed lips. In a single-feed design the top cartridge touches both lips and is commonly used in single-column box magazines, while a staggered feed magazine (sometimes called "double-feed" magazine, not to be confused with the firearm malfunction) consists of a wider set of lips so that the second cartridge in line forces the top cartridge against one of the lips. The staggered-feed design has proven more resistant to jamming in use with double-column magazines than single-feed variants, since the narrowing of a magazine tube to a single-feed induces extra friction which the magazine springs needs to overcome. Some magazine types are strongly associated with certain firearm types, such as the fixed "tubular" magazine found on most modern lever-action rifles and pump-action shotguns. A firearm using detachable magazines may accept a variety of types of magazine, such as the Thompson submachine gun, most variations of which would accept box or drum magazines. Some types of firearm, such as the M249 and other squad automatic weapons, can feed from both magazines and belts.

Tubular

Many of the first repeating rifles and shotguns, particularly lever-action rifles and pump-action shotguns, used magazines that stored cartridges nose-to-end inside of a spring-loaded tube that typically ran parallel underneath the barrel or inside of the buttstock. Tubular magazines are also commonly used in .22 caliber bolt-action rimfire rifles, such as the Marlin Model XT. Tubular magazines and centerfire cartridges with pointed (spitzer) bullets present a safety issue: a pointed bullet may (through the forces of recoil or simply rough handling) strike the next round's primer and ignite that round or even other rounds via chain ignition within the magazine. The Winchester Model 1873 used blunt-nosed centerfire cartridges such as the .44-40 Winchester. Certain modern rifle cartridges using soft-pointed plastic tips have been designed to avoid this problem while improving the aerodynamic qualities of the bullet to match those available in bolt-action designs, therefore extending the effective range of lever-actions.

Box

The most popular type of magazine in modern rifles and handguns, box magazines, arrange the cartridges in columns, either in a single stack or in a double-column or double-stack staggered (zigzag) fashion providing about twice the capacity of a single-stack magazine of the same length. As the firearm cycles, a spring-loaded follower drives the cartridges toward the end of the magazine, ultimately terminating in either a single position (center-feed) or alternating between left and right positions (staggered-feed). Box magazines may be integral to the firearm or removable:

An integral box or fixed box magazine (also known as a blind box magazine when lacking a removable floorplate) is built into the firearm and is not easily removable. This type of magazine is found most often on bolt-action rifles. An integral box magazine is usually charged through the action, one round at a time. Military rifles often use stripper clips, a.k.a. chargers, permitting multiple rounds, commonly with 5 or 10 at a time, to be loaded in rapid sequence. Some integral box magazines use en bloc clips that are loaded into the magazine with the ammunition and that are ejected from the firearm when empty.

A detachable box magazine is a self-contained mechanism capable of being loaded or unloaded while detached from the host firearm. They are attached via a slot in the firearm receiver, usually below the action, to the side of the action, or on top of the action. When necessary, the magazine can easily be detached from the firearm and replaced by another. This significantly speeds the process of reloading, allowing the operator quick access to ammunition. This type of magazine may be straight or curved. Curved or "banana" magazines are necessary if the rifle uses rimmed ammunition or ammunition with a tapered case. Detachable box magazines may be metal or plastic. The plastic magazines are sometimes partially transparent so the operator can easily check the remaining ammunition. Box magazines are often affixed to each other with clamps, clips, tape, straps, or built-in studs to facilitate faster reloading: see jungle style.

There are, however, exceptions to these rules. The Lee–Enfield rifle had a detachable box magazine only to facilitate cleaning. The Lee–Enfield magazine did open, permitting rapid unloading of the magazine without having to operate the bolt-action repeatedly to unload the magazine. Other designs, such as the Breda Modello 30, had a fixed protruding magazine from the right side that resembled a conventional detachable box, but it was not detachable and was reloaded by using 20 round stripper clips.

Rotary

The rotary (or spool) magazine consists of a cylindrical sprocket actuated by a torsion spring, with cartridges fitting between the tooth bar of the sprocket, which is mounted on a spindle parallel to the bore axis and rotates each round sequentially into the feeding position. Rotary magazines may be fixed or detachable, and are usually of low capacity, generally 5 to 10 rounds, depending on the caliber used. John Smith patented a rotary magazine in 1856. Another rotary magazine was produced by Sylvester Roper in 1866 and was also used in the weapons by Anton Spitalsky and the Savage Model 1892. Otto Schönauer first patented a spool magazine in 1886 and his later design, patented in 1900, was used on bolt-action rifles produced at least until 1979, among them Mannlicher–Schönauer adopted by the Greek Army in 1903. The M1941 Johnson rifle and M1947 Johnson auto carbine uses rotary magazines. The design is still used in some modern firearms, most notably the Ruger American series, the semi-automatic Ruger 10/22, the bolt-action Ruger 77/22 and the Steyr SSG 69.

A capsule magazine functions similar to a box magazine, but the spring and follower is stowed away when the magazine bottom is flipped open. The cartridges are loosely dumped into the magazine and spring-fed to the chamber when the bottom is closed.

On the Krag-Jørgensen the magazine is wrapped around the bolt-action to save vertical space and ease loading from the side.

The Krag-Jorgensen bolt-action rifle is the only firearm to use this type of magazine and it was adopted by the militaries of Denmark, Norway, and the United States in the late 19th century.

Much like a rotary magazine, these use an internal continuous chain that works like a conveyor belt. The ARCO Abider, Marek MSG 3J, Ruger 10/22, Sosso 1941 pistol, Small Arms Ltd. Model 2, Moruzh-2 and the Heckler & Koch LMG 11 use these magazines.

Drum

Drum magazines are used primarily for light machine guns. In one type, a moving partition within a cylindrical chamber forces loose rounds into an exit slot, with the cartridges being stored parallel to the axis of rotation. After loading of the magazine, a wound spring or other mechanism forces the partition against the rounds. In all models a single column is pushed by a follower through a curved path. From there the rounds enter the vertical riser either from a single or dual drums. Cylindrical designs such as rotary and drum magazines allow for larger capacity than box magazines, without growing to excessive length. The downside of a drum magazine's extra capacity is its added weight that, combined with the gun, can affect handling and prolonged use. Drum magazines can be more difficult to incorporate into combat gear compared to more regular, rectangular box magazines.

Many drum-fed firearms can also load from conventional box magazines, such as the Soviet PPSh-41 submachine gun, RPK light machine gun, and the American Thompson submachine gun.

The term "drum" is sometimes applied to a belt box for a belt-fed machine gun, though this is just a case that houses a length of ammunition belt, not a drum magazine.

Before WWII the Germans developed 75-round saddle-drum magazines for use in their MG 13 and MG 15 machine guns. The MG 34 machine guns could also use saddle-drum magazine when fitted with a special feed cover. The 75 rounds of ammunition were evenly distributed in each side of the magazine with a central feed "tower" where the ammunition is fed to the bolt. The ammunition was fed by a spring force, with rounds alternating from each side of the double drum so that the gun would not become unbalanced.

Pan

Pan magazines differ from other circular magazines in that the cartridges are stored perpendicular to the axis of rotation, rather than parallel, and are usually mounted on top of the firearm. This type is used on the Lewis Gun, Vickers K, Bren Gun (only used in anti-aircraft mountings), Degtyaryov light machine gun, and American-180 submachine gun. The Type 89 machine gun was, highly unusually, fed from two 45-round quadrant-shaped pan magazines, each holding nine five-round stripper clips.

Helical

Helical magazines extend the drum magazine design so that rounds follow a spiral path around an auger-shaped rotating follower or drive member, allowing for large ammunition capacity in a relatively compact package (compared to a regular box magazine of similar capacity). Early helical magazine designs include that patented by an unidentified inventor through the patent agent William Edward Newton in 1857 and the integral magazine of the Evans Repeating Rifle, patented in the late 1860s. This type of magazine is used by the Calico M960, PP-19 Bizon, CS/LS06 and KBP PP90M1. The North Korean military uses a 100- to 150-round helical magazine in the Type 88 assault rifle. Helical magazines carry substantially more ammunition but are inherently complex, which can make them difficult to load and less reliable in operation.

Hopper

The Japanese Type 11 light machine gun was the only weapon system that used a hopper magazine. This gun was fed by standard 6.5×50mmSR Arisaka stripper clips that were used by riflemen armed with the Type 38 bolt action rifle. The hopper was located on the left side of the receiver and held six of the 5-round clips, for a total of 30 rounds of ammunition. The hopper magazine was designed with a series of mechanical teeth activated by a cam track on the gas piston to pull cartridges off each clip and into the action. After the fifth and final round from each stripper clip was fed and fired, the empty clip would fall out the bottom of the hopper magazine and the next fully loaded stripper clip would then be dropped into place for feeding. There was a spring-loaded follower that applied pressure on top of the clips to hold them in place so they would not fall out while the weapon was being transported or fired.

STANAG magazine

A STANAG magazine or NATO magazine is a type of detachable magazine proposed by NATO in October 1980. Shortly after NATO's acceptance of the 5.56×45mm NATO rifle cartridge, Draft Standardization Agreement (STANAG) 4179 was proposed in order to allow NATO members to easily share rifle ammunition and magazines down to the individual soldier level. The U.S. M16 rifle magazine was proposed for standardization. Many NATO members subsequently developed or purchased rifles with the ability to accept this type of magazine. However, the standard was never ratified and remains a "Draft STANAG".

The STANAG magazine concept is only an interface, dimensional, and control (magazine latch, bolt stop, etc.) requirement. Therefore, it not only allows one type of magazine to interface with various weapon systems, but also allows STANAG magazines to be made in various configurations and capacities. The standard STANAG magazines are 20, 30, and 40 round box magazines, but there are many other designs available with capacities ranging from one round to 60 and 100 round casket magazines, 90 round snail-drum magazines, and 100 round and 150 round double-drum magazines.

Design

Magazine design is shaped by its relationship to belt feeding mechanisms, as they land on complementing ends of the spectrum in their roles. A magazine carries a finite, compact supply that can be replaced quickly, while a linked belt provides a larger supply, reducing the need to reload. Because of this, belts favor firearms used in roles where sustained fire is needed. From a design perspective, a belt-fed firearm requires a mechanism to advance the ammunition, as compared to magazine-fed firearms, where the spring is built into the magazine. Therefore, when a belt does need to be replaced, it takes longer to position. If the feeding system jams, replacing the magazine is much faster than fixing the belt, a very desirable aspect when at close quarters. Due to the trade-offs, some dual-feed firearms have been developed, which support both magazines and belts.

While increasing the magazine capacity and reducing the time spent reloading is almost always desirable, it must be balanced against weight, handling, and reliable feeding. Cartridge dimensions and the number of rounds carried determine the volume a magazine requires; the firearm's intended role and the weight of a loaded magazine impose further practical limits. There is a limit to capacity, where increasing further would produce an inconveniently long, unreliable, or heavy magazine. For example, most modern LMGs use two-row box magazines, with a capacity of 30–45 rounds. While four-row box magazines have been devised with a capacity of up to 60 rounds, they were found to be expensive and less reliable.

Magazine position on the firearm varies widely: it may be placed on the top, on the bottom, or on the side. A top-mounted magazine benefits from gravity-assisted feeding and allows the gun itself to be mounted close to the ground. However, the magazine will project above the firearm, producing a more visible silhouette and obstructing the sight line. This requires the sights or magazine to be offset with the result, as in the Bren Gun, of being only able to be sighted from the right shoulder. A side-mounted magazine may reduce the time to reload from a standing position, but it also introduces a highly variable imbalance to the firearm as it empties, and can make carrying the firearm awkward. An underslung magazine leaves the space above the firearm clear, but its length is constrained by ground clearance when firing prone. Limited clearance can also impede magazine changes, and its spring must fight against gravity to lift the cartridges. However, an additional factor in favor of underslung magazines is standardization. Many light machine guns derived from rifles retain an underslung magazine to provide cross-compatibility with their rifle counterparts, simplifying provision and training. Shorter magazines, as in sniper rifles, project less below the firearm and can make a prone firing position more comfortable.

High-capacity magazine bans

A high-capacity magazine ban is a law which bans or otherwise restricts detachable magazines that can hold more than a certain number of rounds of ammunition. The term high-capacity magazine (or hi-capacity or large-capacity) refers to the number of rounds contained in a magazine, though there is no universal definition regarding what is considered high capacity. High-capacity is separately defined in laws. For example, in the United States, the now-expired Federal Assault Weapons Ban of 1994 included limits regarding magazines that could hold more than ten rounds. As of 2024, fourteen U.S. states, and a number of local governments, ban or regulate magazines that they have legally defined as high-capacity. The majority of U.S. states do not ban or regulate any magazines on the basis of capacity.

Australia

In Australia, handgun, semi-automatic rimfire, pump-action and lever-action rifle magazines (excluding tubular magazines like those found in gallery guns or Winchester rifles for manually repeating rifles) holding more than ten rounds, shotgun magazines holding more than five rounds, and bolt-action and straight-pull rifle magazines holding more than 15 rounds are heavily restricted (Category D).

Canada

In Canada, magazines designed for use in semi-automatic centrefire rifles and semi-automatic shotguns are limited to 5 rounds, and magazines designed for use in handguns are limited to 10 rounds. Magazines designed for use in semi-automatic rimfire rifles, as well as manually operated long guns, are exempt from the magazine capacity restrictions.

Russia

In Russia, all magazines for use with any type of firearm except sport handguns and award weapons are limited to no more than 10 rounds.

United Kingdom

There are no capacity restrictions on detachable magazines in the United Kingdom. However, since January 1989, any shotgun with a detachable magazine, or a non-detachable magazine capable of holding more than two cartridges is classed as a Section 1 firearm and must be held on a firearm certificate, which is subject to more stringent requirements than "normal" section 2 shotguns held on a shotgun certificate. Section 2 shotguns include break-barrel guns with no magazine, as well as repeating and semi-automatic guns with fixed two-round magazines. When the 1988 Act was introduced, many guns with larger (often tubular magazines) were brought into compliance by crimping the magazine.

United States

William B. Ruger, a founder of Sturm, Ruger & Co., is often ascribed with providing the impetus for high-capacity magazine restrictions. Ruger proposed that instead of banning firearms, Congress should outlaw magazines holding more than 15 rounds. "No honest man needs more than 10 rounds in any gun," Ruger told Tom Brokaw of NBC News in 1992. On March 30, 1989, Ruger sent a letter to every member of the US Congress stating:

"The best way to address the firepower concern is therefore not to try to outlaw or license many millions of older and perfectly legitimate firearms (which would be a licensing effort of staggering proportions) but to prohibit the possession of high capacity magazines. By a simple, complete and unequivocal ban on large capacity magazines, all the difficulty of defining 'assault rifle' and 'semi-automatic rifles' is eliminated. The large capacity magazine itself, separate or attached to the firearm, becomes the prohibited item. A single amendment to Federal firearms laws could effectively implement these objectives."

William B. Ruger

The National Rifle Association (NRA) and the National Shooting Sports Foundation (NSSF) say defining magazines with capacities greater than nine rounds as high- or large-capacity is mislabeling. The NRA Institute for Legislative Action (NRA-ILA) claims that magazines that can hold more than 10 rounds are standard capacity and dispute the definition of "high capacity" in bans.

Between 1994 and 2004, the Federal Assault Weapons Ban, which included a ban on high-capacity magazines, was in effect. It prohibited new magazines over 10 rounds in the United States. After the expiration of the ban, there is no nationwide prohibition against the possession of high-capacity magazines, which are considered an unregulated firearm accessory.

Legislation to restore a federal high-capacity magazine ban has been repeatedly introduced by Democrats in the United States Congress since the expiration of the Federal Assault Weapons Ban, especially in the wake of mass shootings in the United States in which high-capacity magazines were used, including the Tucson shooting (2011), the Aurora, Colorado movie theater shooting (2012), and the Harvest music festival shooting (2017). These efforts have been thus far unsuccessful. The federal Keep Americans Safe Act, which would restore the ban on new magazines that hold more than 10 rounds, passed the House Judiciary Committee in September 2019.

Impact

A 2004 study examined the impact of the Federal Assault Weapons Ban (1994 through 2004), which included a prohibition on sales of magazines with capacities over ten rounds. The authors wrote that the ban was not associated with a reduction in firearm homicides or the lethality of gun crimes in general. They suggested this may have been due to the concurrent rise in the use of large capacity magazines with non-banned semiautomatic weapons. The authors noted that high-capacity magazines have a greater potential for affecting gun crime due to the fact that they are also used in firearms not classified as assault weapons. They added, "However, it is not clear how often the ability to fire more than 10 shots without reloading (the current magazine capacity limit) affects the outcomes of gun attacks." Overall the authors reported that there had been "no discernible reduction in the lethality and injuriousness of gun violence, based on indicators like the percentage of gun crimes resulting in death or the share of gunfire incidents resulting in injury, as we might have expected had the ban reduced crimes with both AWs and LCMs."

A 2019 Rockefeller Institute of Government study found no statistically significant association between state-level LCM bans and homicide rates.

A 2020 RAND Corporation review of seven studies on the impact of LCM bans on violent crime rates found "inconclusive evidence for the effect of high-capacity magazine bans on total [homicides] and firearm homicides."

A 2019 study examined the effect of large-capacity magazine (LCM) bans on the frequency and lethality of "high-lethality mass shootings" (defined as those resulting in six or more fatalities) in the United States from 1990 to 2017. Of the 69 high-fatality mass shootings in the U.S. over that period, at least 44 (64%) involved LCMs. Attacks involving LCMs "resulted in a 62% higher mean average death toll" than mass shootings in which high-capacity magazines were not used. States which had banned high-capacity magazines had a substantially lower incidence of mass shootings, as well as far fewer fatalities in mass shootings: "The incidence of high-fatality mass shootings in non–LCM ban states was more than double the rate in LCM ban states; the annual number of deaths was more than 3 times higher." The study acknowledged that because 69 incidents over a 28-year period was, for statistical purposes, "a relatively small number and limits the power to detect significant associations," it was possible that the magnitude of the effects detected was overestimated. The study authors "did not have the statistical power (and thus did not even try) to determine whether different aspects of the various LCM laws might have differential effects on the incidence of high-fatality mass shootings."