The Beta C-Mag is a 100-round capacity drum magazine manufactured by the Beta Company. It was designed by Jim Sullivan and first patented in 1987 and has been adapted for use in numerous firearms firing the 5.56×45mm NATO, 7.62×51mm NATO, and 9×19mm Parabellum cartridges. ''C-Mag'' is short for ''century magazine'', referring to its hundred-round capacity. It has two drum units, each of which hold half of the cartridges inserted into the magazine. The latest version of the magazine is available with a transparent backing to allow the user to see the number of rounds remaining in the magazine. A C-Mag loaded with 5.56×45mm NATO ammunition typically weighs about ; a C-Mag loaded with 7.62×51mm NATO ammunition weighs . A version adapted for the

M16 rifle The M16 rifle (officially designated Rifle, Caliber 5.56 mm, M16) is a family of military rifles adapted from the ArmaLite AR-15 rifle for the United States military. The original M16 rifle was a 5.56×45mm automatic rifle with a 20-ro ...

is used by the U.S. military. The magazine design, including drawings, is covered in detail in .

Design

The C-MAG is a compact twin-drum magazine design that accepts up to 100 rounds of ammunition. It consists of two main components: the twin-drum storage housing and an interchangeable feed clip assembly. The storage housing is standard and fits any like-caliber weapon. The feed clip assembly serves as an adapter for the specific weapon. Before loading and after firing, the feed clip is filled with spacer rounds that are an integral part of the magazine. The upper half of the top spacer round is tapered to allow the weapon bolt to close after the last round is fired. The length of the string-set depends on the customized feed clip for the individual weapon. During loading, cartridges are inserted on top of the spacer rounds, through the feed clip and into the drums. The cartridge column splits at the juncture of the feed clip and the housing to distribute the ammunition evenly into the drums in two concentric rows. During firing, spring-driven rotors advance the cartridges in both drums until they meet at a cam blade that merges the cartridges into a single column that feeds up through the feed clip and into the weapon.

Firearms compatible with C-MAG magazines

9×19mm Parabellum *

Colt 9mm SMG The Colt 9mm SMG, also known as the Colt Model 635 or Colt M635, is a 9×19mm Parabellum submachine gun manufactured by Colt, based on the M16 rifle. Design details The Colt 9mm SMG is a closed bolt, blowback operated SMG, rather than the co ...

Heckler & Koch MP5 The Heckler & Koch MP5 (german: Maschinenpistole 5) is a 9x19mm Parabellum submachine gun, developed in the 1960s by a team of engineers from the German small arms manufacturer Heckler & Koch. There are over 100 variants and clones of the MP5, ...

Uzi The Uzi (; he, עוזי, Ūzi; officially cased as UZI) is a family of Israeli open-bolt, blowback-operated submachine guns and machine pistols first designed by Major Uziel "Uzi" Gal in the late 1940s, shortly after the establishment of the ...

Glock Glock is a brand of polymer-Receiver (firearms), framed, Recoil operation#Short recoil operation, short recoil-operated, locked-breech semi-automatic pistols designed and produced by Austrian manufacturer Glock Ges.m.b.H., Glock Ges.m.b.H. The ...

, plus these firearms using a Glock magazine: **

KRISS Vector The KRISS Vector is a series of weapons based upon the parent submachine gun design developed by the American company KRISS USA, formerly Transformational Defense Industries (TDI). They use an unconventional delayed blowback system combined with ...

Gen II **

Kel-Tec SUB-2000 The SUB-2000 is a pistol-caliber carbine manufactured by Kel-Tec CNC Industries of Cocoa, Florida, United States. The rifle is a blowback operated, semi-automatic firearm with its operating spring located in the tubular stock. The weapon feeds ...

CZ Scorpion Evo 3 The Scorpion EVO 3 is a 9mm carbine manufactured by Česká zbrojovka Uherský Brod, the select-fire submachine gun variant is designated A1, and the semi-automatic variant is designated S1. The EVO 3 designation denotes that the firearm is a t ...

5.56×45mm NATO ( STANAG magazine with Mini-14 compatibility) *

FN Minimi The FN Minimi (short for french: Mini Mitrailleuse; "mini machine gun") is a Belgian 5.56mm light machine gun/squad automatic weapon developed by Ernest Vervier for FN Herstal. First introduced in the late 1970s, it is now in service in more tha ...

M249 light machine gun The M249 light machine gun (LMG), also known as the M249 Squad Automatic Weapon (SAW), which continues to be the manufacturer's designation, and formally written as Light Machine Gun, 5.56 mm, M249, is the American adaptation of the Belgian F ...

Ultimax 100 The Ultimax 100 is a Singapore-made 5.56mm light machine gun, developed by the Chartered Industries of Singapore (CIS, now ST Kinetics) by a team of engineers under the guidance of American firearms designer L. James Sullivan. The weapon is extr ...

AR-15 An AR-15-style rifle is any lightweight semi-automatic rifle based on the Colt AR-15 design. The original ArmaLite AR-15 is a scaled-down derivative of Eugene Stoner's ArmaLite AR-10 design. The then Fairchild Engine and Airplane Corporatio ...

Beretta ARX-160 The Beretta ARX160 is an Italian modular assault rifle manufactured by Beretta. Developed for the Italian Armed Forces as part of the ''Soldato Futuro'' (English: "Future Soldier") program, the ARX160 was launched in 2008 as a commercial weapon ...

FN SCAR The FN SCAR (Special Operations Forces Combat Assault Rifle) is a family of gas-operated short-stroke gas piston automatic rifles developed by Belgian manufacturer FN Herstal (FN) in 2004. It is constructed with modularity for the United State ...

Heckler & Koch G36 The Heckler & Koch G36 (Gewehr 36) is a 5.56×45mm assault rifle designed in the early 1990s by German weapons manufacturer Heckler & Koch as a replacement for the heavier 7.62×51mm G3 battle rifle. It was accepted into service with the ''Bu ...

Heckler & Koch HK33 The Heckler & Koch HK33 is a 5.56mm assault rifle developed in the 1960s by West German armament manufacturer Heckler & Koch GmbH (H&K), primarily for export. Building on the success of their G3 design, the company developed a family of smal ...

Heckler & Koch HK416 The Heckler & Koch HK416 is a gas-operated assault rifle chambered for the 5.56×45mm NATO cartridge. It is designed and manufactured by the German company Heckler & Koch. Although the design is based on the AR-15 class of firearm (specifical ...

* Heckler & Koch HK 93 *

Heckler & Koch XM8 The Heckler & Koch XM8 is a lightweight assault rifle system developed from the late 1990s to early 2000s. The rifle was designed by German small arms manufacturer Heckler & Koch (H&K), and shares design and engineering with their G36 rifle. ...

M4 carbine The M4 carbine (officially Carbine, Caliber 5.56 mm, M4) is a 5.56×45mm NATO, gas-operated, magazine-fed carbine developed in the United States during the 1980s. It is a shortened version of the M16A2 assault rifle. The M4 is extensively ...

PVAR rifle UDMC PVAR rifles are Filipino variants of the Armalite AR-15 and AR-10 using the Pneumatic Valve and Rod system manufactured by United Defense Manufacturing Corporation. The Pneumatic Valve and Rod system was created to be a more reliable alt ...

* Ruger Mini-14 *

SA80 The SA80 (Small Arms for the 1980s) is a British family of 5.56×45mm NATO service weapons used by the British Army. The L85 Rifle variant has been the standard issue service rifle of the British Armed Forces since 1987, replacing the L1A1 Se ...

* SIG SG550 / 551 / 552 / 553 / 556 * Steyr AUG *

CZ 805 BREN The CZ 805 BREN is a gas-operated modular assault rifle designed and manufactured by Česká zbrojovka Uherský Brod. The modular design enables users to change the calibre of the weapon to 5.56×45mm NATO or 7.62×39mm intermediate cartridges by ...

7.62×51mm NATO * AR-10A, and various firearms using

SR-25 pattern magazine An SR-25, AR-10 or LR-308 pattern magazine is a type of detachable firearm magazine based on the original Armalite AR-10 "waffle" magazine design introduced in the late 1950s, used for .308 Winchester and 7.62×51mm NATO cartridges. The design has ...

s. * FN FAL (no longer available) *

(modified FAL-pattern) * Heckler & Koch HK91 and

Heckler & Koch G3 The Heckler & Koch G3 (''Gewehr'' 3) is a 7.62×51mm NATO, select-fire battle rifle developed in the 1950s by the German armament manufacturer Heckler & Koch (H&K) in collaboration with the Spanish state-owned design and development agency CET ...

M14 rifle The M14 rifle, officially the United States Rifle, Caliber 7.62 mm, M14, is an American selective fire battle rifle chambered for the 7.62×51mm NATO (.308 in) cartridge. It became the standard-issue rifle for the U.S. military in 1959, r ...

* AR-10B (modified M14-pattern)

Performance evaluations

Reliability

A test in 2003 by U.S. Army soldiers in Afghanistan found the C-Mag unreliable in simulated combat conditions and reported frequent failures to feed among the issues; likewise,

British Armed Forces The British Armed Forces, also known as His Majesty's Armed Forces, are the military forces responsible for the defence of the United Kingdom, its Overseas Territories and the Crown Dependencies. They also promote the UK's wider interests, s ...

trials found that the C-Mag did not give reliable performance when loaded with British-issue ammunition. The Beta C-Mag is not in widespread use by U.S. military forces, and has not been type-classified. In November 2008, the U.S. Army Experimental Task Force (AETF) at

Fort Bliss, Texas Fort Bliss is a United States Army post in New Mexico and Texas, with its headquarters in El Paso, Texas. Named in honor of LTC William Bliss (1815–1853), a mathematics professor who was the son-in-law of President Zachary Taylor, Ft. Bliss h ...

, evaluated six Beta C-Mag magazines. Four magazines—two with black covers and two with clear covers—were used with M4 carbines in three firing scenarios: controlled pair, controlled burst, and rapid fire. According to the memorandum summarizing the evaluation, the four magazines "performed flawlessly in all three scenarios without jams or stoppages." Additionally, two magazines with black covers were evaluated with M249 light machine guns in controlled burst and rapid-fire scenarios. These also performed without "issues," according to the memo, which also notes that soldiers "had only positive comments" about the C-Mag magazines during the After Action Review (AAR). Test-fired with a Heckler & Koch HK91,

and two other Heckler & Koch-based weapons, the 7.62mm C-Mag was found to operate without problems in either loading or firing at rates up to 1,000 rounds per minute.

References

External links