Heckler & Koch HK21 vs Remington Model 870

ASmall arms

Heckler & Koch HK21

General-purpose machine gun (HK21) Light machine gun (HK23) Heavy machine gun (HK25)

Credit

Armémuseum (The Swedish Army Museum) · CC BY-SA 4.0 · Resized · CC BY-SA 4.0 · Source ↗ · Modified

BSmall arms

Remington Model 870

Pump-action shotgun

First system

Second system

At a glance

Side by side

Length comparisonOne shared metre scale

Heckler & Koch HK21HK25

1.4 m

Length source ↗

Remington Model 870Remington Model 870 · Length · Length

0.67–1.28 m

Length source ↗

Lengths retain their source configuration and measurement scope.

Measured figures

Head to head

17 of 59 rows sourced on both sides

1.4mHK25

0.67–1.28mRemington Model 870 · Length · Length

LengthScopes differ

All recorded figures & sources

1.03 m

HK13E

Single source

1.14 m

HK21E

Single source

1.021 m

HK21 HK21A1, HK11A1, HK11E, HK23E

Single source

1.4 m

HK25

Single source

HK21: 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]

0.67–1.28 m

Remington Model 870 · Length · Length

Single source

26.3 in (670 mm) to 50.5 in (1,280 mm)^[source]Remington Model 870 · Length

16.3kgHK25

3.2–3.6kgRemington Model 870 · Mass · Mass

MassScopes differ

All recorded figures & sources

7.7 kg

HK11A1

Single source

8.15 kg

HK11E

Single source

8 kg

HK13E

Single source

7.92 kg

HK21

Single source

8.3 kg

HK21A1

Single source

9.3 kg

HK21E

Single source

8.75 kg

HK23E

Single source

16.3 kg

HK25

Single source

HK21: 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]

3.2–3.6 kg

Remington Model 870 · Mass · Mass

Single source

7.0 lb (3.2 kg) to 8.0 lb (3.6 kg)^[source]Remington Model 870 · Mass

0.1–1.2kmEffective; sight adjustments

—

Range

All recorded figures & sources

0.1–1.2 km

Effective; sight adjustments

Single source

100–1,200 m (109–1,312 yd) sight adjustments^[source]

900mmHK25

710mm

Barrel lengthScopes differ

All recorded figures & sources

0.56 m

HK21E

Single source

0.45 m

HK21, HK21A1, HK11A1, HK11E, HK23E, HK13E

Single source

0.9 m

HK25

Single source

HK21, HK21A1, HK11A1, HK11E, HK23E, HK13E: 450 mm (17.7 in) HK21E: 560 mm (22.0 in) HK25: 900 mm (35.4 in)^[source]

0.64 m

Remington 870 · 410 Turkey TSS · Barrel length

Single source

0.508 m

Remington 870 · Fieldmaster · 28, 26, 21, 18.75, 26 and 711, 660, 533, 476, 660 and

Single source

0.508 m

Remington 870 · Fieldmaster · Barrel length

Single source

0.51 m

Remington 870 · FieldMaster Deer · Barrel length

Single source

0.51 m

Remington 870 · Fieldmaster Fully Rifled Cantilever · Barrel length

Single source

0.508 m

Remington 870 · Fieldmaster Synthetic · 28, 26, 21, 21 and 710, 660, 530, 530 and

Single source

0.51 m

Remington 870 · Fieldmaster Synthetic · Barrel length

Single source

0.47 m

Remington 870 · Special Purpose Marine Magnum · Barrel length

Single source

0.51 m

Remington 870 · SPS Super Mag Turkey Predator · Barrel length

Single source

0.65 m

Remington 870 · SPS Superslug · Barrel length

Single source

0.71 m

Remington 870 · Super Magnum Flyaway · Barrel length

Single source

0.66 m

Remington 870 · Super Magnum Turkey/Waterfowl Camo · Barrel length

Single source

0.53 m

Remington 870 · Turkey Camo · Barrel length

Single source

0.64–0.71 m

Remington 870 · Wingmaster · Barrel length

Single source

0.36–0.76 m

Remington Model 870 · Barrel length · Barrel length

Single source

14 in (360 mm) to 30 in (760 mm)^[source]Remington Model 870 · Barrel length

20 in (510 mm)^[source]Remington 870 · FieldMaster Deer

25 in (640 mm)^[source]Remington 870 · 410 Turkey TSS

21 in (530 mm)^[source]Remington 870 · Turkey Camo

25 + 1 ⁄ 2 in (650 mm)^[source]Remington 870 · SPS Superslug

28, 26, 21, 18.75, 26 and 20 in (711, 660, 533, 476, 660 and 508 mm)^[source]Remington 870 · Fieldmaster

28, 26, 21, 21 and 20 in (710, 660, 530, 530 and 510 mm)^[source]Remington 870 · Fieldmaster Synthetic

18 + 1 ⁄ 2 in (470 mm)^[source]Remington 870 · Special Purpose Marine Magnum

20 in (510 mm)^[source]Remington 870 · SPS Super Mag Turkey Predator

28 in (710 mm)^[source]Remington 870 · Super Magnum Flyaway

26 in (660 mm)^[source]Remington 870 · Super Magnum Turkey/Waterfowl Camo

25–28 in (640–710 mm)^[source]Remington 870 · Wingmaster

20 in (510 mm)^[source]Remington 870 · Fieldmaster Fully Rifled Cantilever

900rpmHK21, HK21A1 HK11A1, HK21E

—

Rate of fire

All recorded figures & sources

800 rounds/min

HK11E HK23E

Single source

750 rounds/min

HK13E

Single source

900 rounds/min

HK21, HK21A1 HK11A1, HK21E

Single source

450 rounds/min

HK25

Single source

HK21, HK21A1: 900 rounds/min HK11A1, HK21E, HK11E: 800 rounds/min HK23E, HK13E: 750 rounds/min HK25: 450 rounds/min^[source]

915m/sHK25

—

Muzzle velocity

All recorded figures & sources

910 m/s

HK13E using the SS109 cartridge

Single source

840 m/s

HK21E HK23E

Single source

800 m/s

HK21, HK21A1, HK11A1, HK11E

Single source

915 m/s

HK25

Single source

HK21, 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.

Configuration

Details

Heckler & Koch HK21 and Remington Model 870 configuration
Specification	Heckler & Koch HK21	Remington Model 870
Type	General-purpose machine gun (HK21) Light machine gun (HK23) Heavy machine gun (HK25)^[source]	Pump-action shotgun^[source]Remington Model 870 · Type
Place of origin	West Germany^[source]	United States^[source]Remington Model 870 · Place of origin
In service	1961–present^[source]	1950–present^[source]Remington Model 870 · In service
Used by	See Users^[source]	See Users^[source]Remington Model 870 · Used by
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]	Vietnam War Rhodesian Bush War Lebanese Civil War War in Afghanistan Iraq War^[source]Remington Model 870 · Wars
Designer	Heckler & Koch^[source]	L.Ray Crittendon, Phillip Haskell, Ellis Hailston, G.E. Pinckney^[source]Remington Model 870 · Designer
Designed	1961^[source]	1950^[source]Remington Model 870 · Designed
Manufacturer	Heckler & Koch Fábrica de Braço de Prata SEDENA^[source]	Remington Arms^[source]Remington Model 870 · Manufacturer
Produced	1961–1990^[source]	1951–present^[source]Remington Model 870 · Produced
Variants	See Variants^[source]	See Variants^[source]Remington Model 870 · Variants
Cartridge	HK21, HK21A1, HK11A1, HK21E, HK11E: 7.62×51mm NATO HK23E, HK13E: 5.56×45mm NATO HK25: 12.7×99mm NATO^[source]	12 gauge , 16 gauge , 20 gauge , 28 gauge , or .410 bore^[source]Remington Model 870 · Cartridge 12-gauge^[source]Remington 870 · FieldMaster Deer .410-bore^[source]Remington 870 · 410 Turkey TSS 12-gauge^[source]Remington 870 · Turkey Camo 12-gauge^[source]Remington 870 · SPS Superslug 12-gauge, 20-gauge^[source]Remington 870 · Fieldmaster 12-gauge, 20-gauge^[source]Remington 870 · Fieldmaster Synthetic 12-gauge^[source]Remington 870 · Special Purpose Marine Magnum 12-gauge ( 2 + 3 ⁄ 4 ", 3" and 3 + 1 ⁄ 2 ")^[source]Remington 870 · SPS Super Mag Turkey Predator 12-gauge ( 2 + 3 ⁄ 4 ", 3" and 3 + 1 ⁄ 2 ")^[source]Remington 870 · Super Magnum Flyaway 12-gauge ( 2 + 3 ⁄ 4 ", 3" and 3 + 1 ⁄ 2 ")^[source]Remington 870 · Super Magnum Turkey/Waterfowl Camo 12-gauge ( 2 + 3 ⁄ 4 " and 3"), 20-gauge, and .410-bore^[source]Remington 870 · Wingmaster 12-gauge^[source]Remington 870 · Fieldmaster Fully Rifled Cantilever
Action	Roller-delayed blowback , closed bolt^[source]	Pump-action^[source]Remington Model 870 · Action
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]	3+1, 4+1, 5+1, 6+1, or 7+1 round internal tube magazine , or an external 6+1 box magazine^[source]Remington Model 870 · Feed system
Sights	Rear rotary diopter drum; hooded front post^[source]	Bead, twin bead, adjustable open sights, or ghost ring (all iron sights ). Also cantilever and receiver-mounts for scopes^[source]Remington Model 870 · Sights
Former operator · Portugal	Portugal^[source]	—
Role	German 7.62×51mm NATO general-purpose machine gun ,^[source]	—
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	—
Unit cost	—	$ 350^[source]Remington Model 870 · Unit cost
No. built	—	11,000,000+^[source]Remington Model 870 · No. built
Barrel type	—	Fully rifled^[source]Remington 870 · FieldMaster Deer Vent Rib, Rem Choke^[source]Remington 870 · 410 Turkey TSS Vent Rib, Rem Choke^[source]Remington 870 · Turkey Camo Fully rifled extra heavy (fluted)^[source]Remington 870 · SPS Superslug Vent rib Rem Choke and fully rifled^[source]Remington 870 · Fieldmaster Vent rib Rem Choke and fully rifled^[source]Remington 870 · Fieldmaster Synthetic Cylinder choke^[source]Remington 870 · Special Purpose Marine Magnum Rem Choke^[source]Remington 870 · SPS Super Mag Turkey Predator Vent rib, Rem Choke^[source]Remington 870 · Super Magnum Flyaway Vent rib, Rem Choke^[source]Remington 870 · Super Magnum Turkey/Waterfowl Camo Vent Rib, Rem Choke^[source]Remington 870 · Wingmaster Fully rifled^[source]Remington 870 · Fieldmaster Fully Rifled Cantilever
Reported operators	Reported operator · Argentina Reported operator · Bangladesh Reported operator · Brazil Reported operator · Bolivia Reported operator · Brunei Reported operator · Cameroon Reported operator · Croatia Reported operator · Cyprus Reported operator · Ecuador Reported operator · El Salvador Reported operator · Germany Reported operator · Greece Reported operator · Jordan Reported operator · Kenya Reported operator · Latvia Reported operator · Malaysia Reported operator · Mauritius Reported operator · Mexico Reported operator · Niger Reported operator · Nigeria Reported operator · Paraguay Reported operator · Peru Reported operator · Qatar Reported operator · Senegal Reported operator · Sri Lanka Reported operator · South Africa Reported operator · Sudan Reported operator · Sweden Reported operator · Thailand Reported operator · Turkey Reported operator · Uganda Reported operator · United Arab Emirates Reported operator · United States	—

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Heckler & Koch HK21

Remington Model 870

Type

General-purpose machine gun (HK21) Light machine gun (HK23) Heavy machine gun (HK25)^[source]

Pump-action shotgun^[source]Remington Model 870 · Type

Place of origin

West Germany^[source]

United States^[source]Remington Model 870 · Place of origin

In service

1961–present^[source]

1950–present^[source]Remington Model 870 · In service

Used by

See Users^[source]

See Users^[source]Remington Model 870 · Used by

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]

Vietnam War Rhodesian Bush War Lebanese Civil War War in Afghanistan Iraq War^[source]Remington Model 870 · Wars

Designer

Heckler & Koch^[source]

L.Ray Crittendon, Phillip Haskell, Ellis Hailston, G.E. Pinckney^[source]Remington Model 870 · Designer

Designed

1961^[source]

1950^[source]Remington Model 870 · Designed

Manufacturer

Heckler & Koch Fábrica de Braço de Prata SEDENA^[source]

Remington Arms^[source]Remington Model 870 · Manufacturer

Produced

1961–1990^[source]

1951–present^[source]Remington Model 870 · Produced

Variants

See Variants^[source]

See Variants^[source]Remington Model 870 · Variants

Cartridge

HK21, HK21A1, HK11A1, HK21E, HK11E: 7.62×51mm NATO HK23E, HK13E: 5.56×45mm NATO HK25: 12.7×99mm NATO^[source]

12 gauge , 16 gauge , 20 gauge , 28 gauge , or .410 bore^[source]Remington Model 870 · Cartridge

12-gauge^[source]Remington 870 · FieldMaster Deer

.410-bore^[source]Remington 870 · 410 Turkey TSS

12-gauge^[source]Remington 870 · Turkey Camo

12-gauge^[source]Remington 870 · SPS Superslug

12-gauge, 20-gauge^[source]Remington 870 · Fieldmaster

12-gauge, 20-gauge^[source]Remington 870 · Fieldmaster Synthetic

12-gauge^[source]Remington 870 · Special Purpose Marine Magnum

12-gauge ( 2 + 3 ⁄ 4 ", 3" and 3 + 1 ⁄ 2 ")^[source]Remington 870 · SPS Super Mag Turkey Predator

12-gauge ( 2 + 3 ⁄ 4 ", 3" and 3 + 1 ⁄ 2 ")^[source]Remington 870 · Super Magnum Flyaway

12-gauge ( 2 + 3 ⁄ 4 ", 3" and 3 + 1 ⁄ 2 ")^[source]Remington 870 · Super Magnum Turkey/Waterfowl Camo

12-gauge ( 2 + 3 ⁄ 4 " and 3"), 20-gauge, and .410-bore^[source]Remington 870 · Wingmaster

12-gauge^[source]Remington 870 · Fieldmaster Fully Rifled Cantilever

Action

Roller-delayed blowback , closed bolt^[source]

Pump-action^[source]Remington Model 870 · Action

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]

3+1, 4+1, 5+1, 6+1, or 7+1 round internal tube magazine , or an external 6+1 box magazine^[source]Remington Model 870 · Feed system

Sights

Rear rotary diopter drum; hooded front post^[source]

Bead, twin bead, adjustable open sights, or ghost ring (all iron sights ). Also cantilever and receiver-mounts for scopes^[source]Remington Model 870 · Sights

Former operator · Portugal

Portugal^[source]

—

Role

German 7.62×51mm NATO general-purpose machine gun ,^[source]

—

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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Unit cost

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$ 350^[source]Remington Model 870 · Unit cost

No. built

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11,000,000+^[source]Remington Model 870 · No. built

Barrel type

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Fully rifled^[source]Remington 870 · FieldMaster Deer

Vent Rib, Rem Choke^[source]Remington 870 · 410 Turkey TSS

Vent Rib, Rem Choke^[source]Remington 870 · Turkey Camo

Fully rifled extra heavy (fluted)^[source]Remington 870 · SPS Superslug

Vent rib Rem Choke and fully rifled^[source]Remington 870 · Fieldmaster

Vent rib Rem Choke and fully rifled^[source]Remington 870 · Fieldmaster Synthetic

Cylinder choke^[source]Remington 870 · Special Purpose Marine Magnum

Rem Choke^[source]Remington 870 · SPS Super Mag Turkey Predator

Vent rib, Rem Choke^[source]Remington 870 · Super Magnum Flyaway

Vent rib, Rem Choke^[source]Remington 870 · Super Magnum Turkey/Waterfowl Camo

Vent Rib, Rem Choke^[source]Remington 870 · Wingmaster

Fully rifled^[source]Remington 870 · Fieldmaster Fully Rifled Cantilever

Reported operators

Reported operator · Argentina
Reported operator · Bangladesh
Reported operator · Brazil
Reported operator · Bolivia
Reported operator · Brunei
Reported operator · Cameroon
Reported operator · Croatia
Reported operator · Cyprus
Reported operator · Ecuador
Reported operator · El Salvador
Reported operator · Germany
Reported operator · Greece
Reported operator · Jordan
Reported operator · Kenya
Reported operator · Latvia
Reported operator · Malaysia
Reported operator · Mauritius
Reported operator · Mexico
Reported operator · Niger
Reported operator · Nigeria
Reported operator · Paraguay
Reported operator · Peru
Reported operator · Qatar
Reported operator · Senegal
Reported operator · Sri Lanka
Reported operator · South Africa
Reported operator · Sudan
Reported operator · Sweden
Reported operator · Thailand
Reported operator · Turkey
Reported operator · Uganda
Reported operator · United Arab Emirates
Reported operator · United States

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