Heckler & Koch HK33
June 19, 2008
The HK33 is a 5.56 mm assault rifle developed in the 1960s by West German armament manufacturer Heckler & Koch GmbH (HK), primarily for export. Capitalizing on the success of the G3 design, the company developed a family of small arms (all using the G3 operating principle and basic design concept) consisting of four types of firearms: the first type, chambered in 7.62×51mm NATO, second – using the 7.62×39mm M43 round, third – the intermediate 5.56×45mm caliber and the fourth type – chambered for the 9×19mm Parabellum pistol cartridge.
The HK33 series of rifles were adopted by the Brazilian Air Force (Força Aérea Brasileira, FAB), the armed forces of Thailand and Malaysia where they were produced under a license agreement. The rifle was also license-built in France by MAS, and in Turkey by MKEK. The HK33 is no longer marketed by Heckler & Koch.

Variants
The HK33 is available in several configurations: the HK33A2 (fitted with a rigid synthetic stock), an accurized variant known as the HK33SG/1 (with a telescopic optical sight and improved trigger analogous to the one used in the G3SG/1), HK33A3 (with a telescoping metal stock), the HK33KA3 carbine (barrel reduced in length to the base of the front sight post also equipped with a folding metal stock; the short barrel cannot be used to launch rifle grenades or attach a bayonet) as well as the compact HK53 carbine, which features a short, 211 mm barrel, a forearm derived from the Heckler & Koch MP5 submachine gun and a telescoping stock or a receiver endplate cover (later models also received an open-style flash hider).
An Ecuadoran Marine armed with an HK33E rifle.
The HK13 light machine gun was also built based on the HK33. It is fed from either box or drum magazines (the latter has a 100-round capacity), has a quick-change heavy barrel for sustained fire, shrouded with a sheet metal heat guard (replacing the synthetic forearm) and a 2-point bipod adapter.
Heckler & Koch also make a semi-automatic only variant of the HK33A2 for the civilian shooting market designated the HK93.
The rifle is disassembled into the following components for maintenance: the receiver, stock with return spring and trigger pack with pistol grip. The trigger groups can be swapped out to meet the user’s specific mission requirements. HK offers several different trigger assemblies: a three-shot burst fire control group with selector lever/safety (selector settings: “0” – weapon is safe, “1” – single fire, “2” – 2-round burst or “3” – burst, 3-rounds; the selector lever is ambidextrous); a “Navy” trigger unit (three settings: safe, semi and full auto fire) and a four-position trigger group (selector settings: weapon safe, single fire, 3-round burst and automatic fire).

Type Assault rifle
Place of origin West Germany
Service history
Used by See Users
Production history
Designer Heckler & Koch
Manufacturer Heckler & Koch, MAS, MKEK
Variants See Variants
Specifications
Weight 3.65 kg (8.05 lb) (HK33A2)
3.98 kg (8.8 lb) (HK33A3)
3.89 kg (8.6 lb) (HK33KA3)
3.05 kg (6.7 lb) (HK53)
Length 920 mm (36.2 in) (HK33A2)
940 mm (37.0 in) stock extended / 735 mm (28.9 in) stock collapsed (HK33A3)
865 mm (34.1 in) stock extended / 675 mm (26.6 in) stock collapsed (HK33KA3)
755 mm (29.7 in) stock extended / 563 mm (22.2 in) stock collapsed (HK53)
Barrel length 390 mm (15.4 in) (HK33A2)
332 mm (13.1 in) (HK33KA3)
225 mm (8.9 in) (HK53)
Cartridge 5.56×45mm NATO
Action Roller-delayed blowback
Rate of fire 750 rounds/min (HK33A2)
700 rounds/min (HK53)
Muzzle velocity 950 m/s (3,117 ft/s) (HK33A2)
880 m/s (2,887.1 ft/s) (HK33KA3)
750 m/s (2,460.6 ft/s) (HK53)
Effective range 100 to 400 m sight adjustments
Feed system 25, 30, 40-round detachable box magazine
Sights Rotary rear aperture drum, hooded foresight