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ASmall arms
General-purpose machine gun (HK21) Light machine gun (HK23) Heavy machine gun (HK25)
At a glance
Measured figures
HK13E
Single sourceHK21E
Single sourceConfiguration
| Specification | Heckler & Koch HK21 | LMT Modular Ambidextrous Rifle System |
|---|---|---|
| Type | General-purpose machine gun (HK21) Light machine gun (HK23) Heavy machine gun (HK25)[source] | Assault rifle Battle rifle[source]LMT Modular Ambidextrous Rifle System · Type |
| Place of origin | West Germany[source] | United States[source]LMT Modular Ambidextrous Rifle System · Place of origin |
| In service | 1961–present[source] | 2015 - present[source] |
HK21 HK21A1, HK11A1, HK11E, HK23E
Single sourceHK25
Single sourceHK21: 1,021 mm (40.2 in) HK21A1, HK11A1, HK11E, HK23E, HK13E: 1,030 mm (40.6 in) HK21E: 1,140 mm (44.9 in) HK25: 1,400 mm (55.1 in)[source]
LMT Modular Ambidextrous Rifle System · Length · "Maximum"
Single source914 mm (36.0 in) ("Maximum")[source]LMT Modular Ambidextrous Rifle System · Length
HK11A1
Single sourceHK11E
Single sourceHK13E
Single sourceHK21
Single sourceHK21A1
Single sourceHK21E
Single sourceHK23E
Single sourceHK25
Single sourceHK21: 7.92 kg (17.46 lb) HK21A1: 8.30 kg (18.3 lb) HK11A1: 7.70 kg (17.0 lb) HK21E: 9.30 kg (20.5 lb) HK11E: 8.15 kg (18.0 lb) HK23E: 8.75 kg (19.3 lb) HK13E: 8 kg (18 lb) HK25: 16.30 kg (35.9 lb)[source]
LMT Modular Ambidextrous Rifle System · Mass · Empty
Single source3.3kg (empty)[source]LMT Modular Ambidextrous Rifle System · Mass
Effective; sight adjustments
Single source100–1,200 m (109–1,312 yd) sight adjustments[source]
HK21E
Single sourceHK21, HK21A1, HK11A1, HK11E, HK23E, HK13E
Single sourceHK25
Single sourceHK21, HK21A1, HK11A1, HK11E, HK23E, HK13E: 450 mm (17.7 in) HK21E: 560 mm (22.0 in) HK25: 900 mm (35.4 in)[source]
L129A2 exact named variant; not a sibling record · Barrel length
Single sourceStgw 25 exact named variant; not a sibling record · Barrel length
Single sourceHK11E HK23E
Single sourceHK13E
Single sourceHK21, HK21A1 HK11A1, HK21E
Single sourceHK25
Single sourceHK21, HK21A1: 900 rounds/min HK11A1, HK21E, HK11E: 800 rounds/min HK23E, HK13E: 750 rounds/min HK25: 450 rounds/min[source]
HK13E using the SS109 cartridge
Single sourceHK21E HK23E
Single sourceHK21, HK21A1, HK11A1, HK11E
Single sourceHK25
Single sourceHK21, HK21A1, HK11A1, HK11E: 800 m/s (2,625 ft/s) HK21E: 840 m/s (2,756 ft/s) HK23E, HK13E: 910 m/s (2,986 ft/s) (using the SS109 cartridge) HK25: 915 m/s (3,002 ft/s)[source]
Bars compare reported quantities only. A larger figure does not make a system better; configurations and test conditions differ.
| Used by | See Users[source] | — |
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| Wars | Vietnam War Football War Lebanese Civil War Portuguese Colonial War Shaba II South African Border War Kurdish–Turkish conflict Salvadoran Civil War Operation Eagle Claw Sri Lankan Civil War Armed conflict for control of the favelas Boko Haram insurgency[source] | — |
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| Designer | Heckler & Koch[source] | Lewis Machine & Tool Company[source]LMT Modular Ambidextrous Rifle System · Designer |
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| Designed | 1961[source] | — |
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| Manufacturer | Heckler & Koch Fábrica de Braço de Prata SEDENA[source] | Lewis Machine & Tool Company[source]LMT Modular Ambidextrous Rifle System · Manufacturer |
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| Produced | 1961–1990[source] | — |
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| Variants | See Variants[source] | — |
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| Cartridge | HK21, HK21A1, HK11A1, HK21E, HK11E: 7.62×51mm NATO HK23E, HK13E: 5.56×45mm NATO HK25: 12.7×99mm NATO[source] | 5.56×45mm NATO 7.62×51mm NATO 6.5mm Creedmoor[source]LMT Modular Ambidextrous Rifle System · Cartridge The MARS-L (light) assault rifle variants are chambered for the 5.56×45mm NATO intermediate cartridge , and the MARS-H (heavy) battle rifle and designated marksman rifle variants for the 7.62×51mm NATO , 6.5 mm Creedmoor or similar fully powered cartridges .[source]Design · explicit MARS-L/MARS-H cartridge scope MARS-H based designated marksman variant, chambered in 6.5 mm Creedmoor .[source]L129A2 · explicit MARS-L/MARS-H cartridge scope Swiss MARS-H-based designated marksman rifle chambered in 7.62×51mm NATO.[source]7.62mm Zf Stgw 20 · explicit MARS-L/MARS-H cartridge scope LMT's MRGG-A is a member of its Modular Ambidextrous Rifle System-Heavy (MARS-H) family, which are commonly described as AR-10-style rifles, but is chambered to fire the 6.5mm Creedmoor round.[source]MK24 Mid-Range Gas Gun-Assault · explicit MARS-L/MARS-H cartridge scope |
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| Action | Roller-delayed blowback , closed bolt[source] | Gas-operated , rotating bolt (internal piston, not direct impingement ) or Short-stroke piston[source]LMT Modular Ambidextrous Rifle System · Action |
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| Feed system | M13, DM6, DM1 ammunition belt, 20-round detachable box or 50-round drum magazine (from the G3 ). An 80-round drum magazine or even a 100-round drum magazine was also available (No longer manufactured)[source] | 5.56×45mm NATO : 30-round detachable box magazine 7.62×51mm NATO 20-round detachable box magazine[source]LMT Modular Ambidextrous Rifle System · Feed system |
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| Sights | Rear rotary diopter drum; hooded front post[source] | — |
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| Former operator · Portugal | Portugal[source] | — |
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| Role | German 7.62×51mm NATO general-purpose machine gun ,[source] | — |
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| Source measurement | The Heckler & Koch HK21 is a German 7.62×51mm NATO general-purpose machine gun , developed in 1961 by small arms manufacturer Heckler & Koch and based on the HK G3 battle rifle . The machine gun is in use with the armed forces of several Asian, African and Latin American countries. It was also license-manufactured by Fábrica de Braço de Prata in Portugal as the m/968 and in Mexico by SEDENA as the MG21 . In the German military ( Bundeswehr ) and the federal police ( Bundespolizei ) it is designated "G8".[source]Heckler & Koch HK21 · Lead; only the objects and conditions stated in this passage Thus a chambering dependent (4:1 for 7.62×51mm NATO) or (3:1 for 5.56×45mm NATO) transmission ratio is maintained (as long as the rollers move on the inclined surfaces of the barrel extension and locking piece) of the bolt carrier and locking piece relative to the bolt head; the bolt head carrier travels backwards significantly faster than the bolt head, ensuring a safe drop of pressure within the barrel prior to extraction.[source]Heckler & Koch HK21 · Design details / Operating mechanism; only the objects and conditions stated in this passage The HK21 has a free-floating, heavy, quick-change barrel fitted with a slotted flash suppressor . The firearm is equipped with an iron sight line that consist of a rotary rear drum and hooded front post. The rear aperture sight is mechanically adjustable for both windage and elevation from 100 to 1,200 m (109 to 1,312 yd) in 100 m (109 yd) increments for 7.62×51mm NATO models or 100 to 1,000 m (109 to 1,094 yd) in 100 m (109 yd) increments for 5.56×45mm NATO models.[source]Heckler & Koch HK21 · Design details / Features; only the objects and conditions stated in this passage By simply swapping out several components such as the barrel, bolt and feed plate unit, the machine gun can be quickly converted to the intermediate 7.62×39mm and 5.56×45mm NATO chamberings.[source]Heckler & Koch HK21 · Design details / Features; only the objects and conditions stated in this passage In the early 1970s the HK21's design was simplified and the feed mechanism was modified. The machine gun's weight was increased, a carrying handle and a hooked buttstock with improved buffer mechanism were also added. The barrels were internally revised to polygonal rifling . Since then, the HK21 was offered in two main variants: the HK21A1 general-purpose machine gun (with a different belt feed mechanism) and the HK11A1 light machine gun. (optimized for magazine feed only). The HK11A1 proved more successful in export sales and was adopted by the Hellenic Army and several African and Asian armies. Both machine guns, as in the original HK21, can be converted to chamber the 5.56×45mm NATO round by replacing the appropriate components.[source]Heckler & Koch HK21 · Variants / HK21A1; only the objects and conditions stated in this passage HK11E light machine gun (magazine fed, chambered in 7.62×51mm NATO)[source]Heckler & Koch HK21 · Variants / HK21E; only the objects and conditions stated in this passage HK13E light machine gun (magazine fed, chambered in 5.56×45mm NATO)[source]Heckler & Koch HK21 · Variants / HK21E; only the objects and conditions stated in this passage HK21E general-purpose machine gun (belt-fed, 7.62×51mm NATO)[source]Heckler & Koch HK21 · Variants / HK21E; only the objects and conditions stated in this passage The "E model" is a thoroughly revised variant aimed to improve the reliability, efficiency and service life of the HK21. For this the length of the receiver was increased by 25 mm (1.0 in) to provide additional recoil length for the bolt group. The recoil reduction improved accuracy of fire. Reinforcing bars were added to the receiver to provide additional strength and a guaranteed 60,000 rounds minimum service life. The bolt head, extractor and locking roller holder were completely redesigned as were the bolt carrier and recoil spring assembly, belt feed unit, buffer, barrel and trigger group. The redesigned belt feed mechanism transports the ammunition belt in two steps reducing stress on the feed and ammunition belt.[source]Heckler & Koch HK21 · Variants / HK21E; only the objects and conditions stated in this passage Compared to the older HK21A1 and HK11A1, the modernized "Export" machine guns also feature a longer barrel shroud, extended by 94 mm (3.7 in) towards the front, which also resulted in a longer sight radius; the barrel extension was modified (the HK21E also received a longer barrel); a burst fire mode was incorporated into the trigger group as the fourth selector setting (3-round burst); a polymer barrel handle was added; space for a cleaning kit was added in the grip; the rear sight was modified with an adjustable drum; a bipod with a 3-position height adjustment and 30-degree tilt mechanisms replaced the simple folding bipod; the feed mechanism was modified to provide continuous feeding (by moving the belt in two stages, during both forward and rear movement of the bolt), a forward assist for silent loading was provided and the machine guns were adapted to use NATO -standard optical sight mounts.[source]Heckler & Koch HK21 · Variants / HK21E; only the objects and conditions stated in this passage When employed in the light machine gun (infantry assault) role, the HK21E stores its ammunition belt in a 100-round sheet metal container, fastened to the bottom of the feed mechanism (as in the HK21A1). The ability to use Heckler & Koch G3 or STANAG (for HK23E) box or drum magazines is available with an optional feed module kit that consists of the bolt, recoil spring and belt feed module or magazine well. When employed in the belt-fed medium machine gun (fire support) role the HK21E provides a cook-off rate in excess of 1,000 rounds fired in quick succession. The shock-absorbing tripod weighs 10.5 kg (23.1 lb).[source]Heckler & Koch HK21 · Variants / HK21E; only the objects and conditions stated in this passage The HK23 is a belt-fed light machine gun variant, chambered in 5.56×45mm NATO cartridge.[source]Heckler & Koch HK21 · Variants / HK23; only the objects and conditions stated in this passage A heavy machine gun prototype of the HK21 chambered in .50 BMG (12.7×99mm NATO) was proposed but never went into production.[source]Heckler & Koch HK21 · Variants / HK25; only the objects and conditions stated in this passage An aftermarket conversion of an HK21 general purpose machinegun into a belt-fed short carbine created by gunsmiths F. J. Vollmer & Company Inc. The barrel is 8.9 inches long, has an overall length of 21 inches, weighs about 11 lbs. unloaded, and has a rate of fire of 950 to 1,000 rounds per minute. Fixed barrel models have a "Tropical" MP5-style handguard with ventilation slots. Quick-change barrel models have a four-position Picatinny Rail handguard (usually used with a vertical foregrip). It feeds from a 100-round HK21 belt box and uses either the American M13 or German DM6 disintegrating link belt. Vollmer only made 30 guns, 2 of which had quick-change barrels.[source]Heckler & Koch HK21 · Variants / HK51B; only the objects and conditions stated in this passage | — |
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Stgw 25K exact named variant; not a sibling record · Barrel length
Single source