Heckler & Koch HK21
Heckler & Koch · Machine Gun · In Service · 1961
Also known as: HK21A1, m/968, MG21
Overview
The Heckler & Koch HK21 is a German general-purpose machine gun introduced in 1961 and derived from the G3 battle rifle, sharing its roller-delayed blowback action and many components. Chambered in 7.62x51mm NATO, it fires from a closed bolt at roughly 900 rounds per minute and feeds from disintegrating or non-disintegrating belts, with conversion kits allowing magazine feed. Its quick-change barrel and interchangeable feed modules made it a flexible squad and sustained-fire weapon, and it was widely exported and license-produced in Portugal (m/968) and Mexico (MG21).
Specifications
| Weight (empty) | 7300 g (257.5 oz) |
| Overall Length | 1020 mm (40.16") |
| Barrel Length | 450 mm (17.72") |
| Action Type | Roller Delayed Blowback |
| Firing Mechanism | Hammer Fired |
| Trigger Type | Single Stage |
| Magazine Type | Belt |
| Muzzle Velocity | 823 m/s (2700 fps) |
| Muzzle Energy | 3226 J (2379 ft·lbf) |
| Effective Range | 1200 m (1312 yd) |
| Maximum Range | 3500 m (3828 yd) |
| Rate of Fire | 900 rpm |
| Barrel Rifling | Right Hand |
| Rifling Twist | 305 mm (12.01") |
| Number of Grooves | 4 |
| Frame Material | Steel |
| Barrel Material | Steel |
| Stock Material | Polymer |
| Finish | Phosphate |
Calibers
- 7.62x51mm NATO · primary · 7.62mm NATO — also known as .308 Winchester, 7.62x51mm, .308 Win
Features
- Firing modes: Semi Automatic, Full Automatic
- Feed systems: Disintegrating Belt, Non Disintegrating Belt, Box Magazine With Conversion Kit
- Safety mechanisms: Manual Safety, Selector Lever
- Features: Quick Change Barrel, Closed Bolt Operation, Interchangeable Feed Unit, Bipod, Tripod Mountable, Convertible Belt Or Magazine Feed
Variants
- HK11 — Magazine Fed Automatic Rifle
- HK21A1 — Simplified Production
- HK21E — Export Modernized
- HK11E — Magazine Fed Export
Service history
Operators
- Bundeswehr
- Portuguese Armed Forces · as m/968
- Mexican Armed Forces · as MG21
- Royal Thai Armed Forces
- United States special operations forces
Conflicts
- Portuguese Colonial War (1961-1974)
- Operation Eagle Claw (1980)
Production
Production years: 1961-present
Includes licensed production in Portugal and Mexico; modular 'E' family followed in the 1980s
Origin
Country of origin: Germany
Notes
Belt feed is the standard configuration; a feed-module swap converts the gun to box-magazine feed. The closely related HK11 is the magazine-fed automatic-rifle counterpart. In the 1980s the design was modernized into the modular 'E' family (HK11E/HK13E/HK21E).
Background
Because it is essentially a belt-fed G3, an HK21 gunner can field-strip and understand the action of his squad's rifles and machine gun interchangeably - the roller-delayed bolt is the same family throughout, a deliberate H&K logistics philosophy.