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 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; the second, using the Soviet 7.62×39mm M43 round; the third, chambered in .223 Remington and 5.56×45mm NATO; and the fourth type, chambered for the 9×19mm Parabellum pistol cartridge. Commercially the HK33 was a successful design but it did not sell as well as the G3.

The HK33 series of rifles were adopted by the Brazilian Air Force (Força Aérea Brasileira or FAB), the armed forces of Thailand and Malaysia where they were produced under a licence agreement. The rifle was also licence-built in Turkey by MKEK, and exported from France branded as MAS but actually made in Germany.

The HK33 is a selective fire weapon with Heckler & Koch's roller-delayed blowback system of operation. It employs a two-piece bolt consisting of a bolt head with a pair of rollers and bolt carrier. Upon firing, the two cylindrical rollers in the bolt head are cammed inward by inclined surfaces of the barrel extension and impart a rearward motion on the locking piece, which also propels the bolt carrier rearward. This built-in mechanical disadvantage delays the movement of the bolt head relative to the bolt head carrier which is withdrawing at significant higher velocity of the bolt head. The rollers soon compress entirely into the bolt head, clearing the locking recesses of the barrel extension, and both parts now continue rearward together, opening the breech and actuating the extraction and feeding cycles. The chamber is opened under high pressure, thus the chamber received a series of flutes in order to increase extraction reliability and prevent sticking of the spent casing to the chamber walls.

HK33

Original fixed stock variant with 390mm (15.35") barrel. Used similar furniture to contemporary G3 models.

HK33A1

HK33 with retractable stock. Used a convex buttplate similar to the G3A4.

HK33K

Carbine version of HK33A1 with 322mm (12.67") barrel.[9] Due to the short barrel, the HK33KA1 cannot be used to launch rifle grenades or mount a bayonet.

HK33ZF

HK33 with 4x scope. The ZF stands for Zielfernrohr ("Telescopic Sight").

HK33A2

Improved version of original HK33. The fixed stock was strengthened and the synthetic forearm replaced with a handguard that allows a lightweight bipod to be attached and stowed into two grooves at the base.

HK33A3

HK33A2 with telescoping stock. Early examples have a similar buttplate to the A1, but HK later switched to a concave buttplate similar to the MP5A3.HK33KA2Carbine version of HK33A2 with fixed stock.

HK33KA3

Carbine version of HK33A3 with telescoping stock.

HK33A2ZF

HK33A2 with 4x scope.

HK33E

Later designation used by HK for the HK33 family. The E stood for "export". Different configurations were available which were essentially the same as the HK33A2, HK33A3 and HK33A2ZF.[10]

HK33KE

Later designation used for the HK33KA3.

HK33SG/1

An accurized model of the HK33A2; equipped with a telescopic sight and improved trigger analogous to the one used in the G3SG/1.

HK53

Compact version of the HK33K. Has a short 211 mm (8.3 in) barrel, a forearm derived from the MP5 submachine gun and a telescopic shoulder stock or receiver endplate cover (later models also received a four-prong flash hider).

HK13Light machine gun. 

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.

HK23Machine gun. 

It is fed from a disintegrating belt. It is otherwise the same as the HK13.

Harrington & Richardson T223

Licensed copy of the HK33 made during the mid-1960s[11] to compete with the M16 during the smallbore rifle trials. It was mechanically identical to the HK33, except for slight changes to meet the rifle trials requirements. The selector was marked in English (Safe, S.A. (semi-automatic), and F.A. (full automatic)) rather than German (S for Sicher - "secure", or safe; E for Einzelfeuer - "single fire", or semi-automatic; and F for Feuerstoss - "firing burst", or automatic fire). The adjustable bipod was redesigned so that it had a tab that slotted into a mount behind the forend, rather than clamping to the siderails. It used the early straight-walled aluminum 20-round magazine with a bolt hold-open device. There was a lever inside the front of the trigger guard that would release and close the open bolt. The basic T223 kit came with six 20-round magazines, a bipod with carrying case, a bayonet and scabbard, and a webbing-cloth sling. It could also use the later Hecker & Koch curved 25- or 40-round magazines, which gave it more capacity than the M16's 20- and 30-round magazines.[13] It wasn't a popular seller, as any qualified client outside the US military who wanted an HK33 could just buy one (and most were still buying G3s and FALs). It was no longer featured in the company catalog after 1967 and all stocks were sold off when H&R went bankrupt in 1986.The Navy SEALs trialed it during the Vietnam War with the extended 40-round magazine as standard. Their rifle kit was similar to the commercial box except it came packed with four 40-round magazines instead. Since the magazines wouldn't fit in standard US web gear pouches, SEALs carried them in Chinese-made webgear for AK47 magazines. Although it was popular, the bias against non-American designs, its lack of compatibility with M16 magazines and accessories, and its higher cost than the M16 kept it from being adopted as a standard weapon.Type 11A derivative of the HK33 manufactured in Thailand by the Ministry of National Defence for use by the Thai armed forces. A bullpup variant also exists with M16 sights and foregrip for close combat in jungle environments.

MA-11

A Myanmar-made version of the HK33 assault rifle which was fielded from the late 90s to early 2000s. It was made by KaPaSa in cooperation with Myanmar Fritz Werner Industries alongside engineers from the Electro-Mechanical and Engineering Corps of the Army of Myanmar (EMEC). A bayonet can be mounted underneath the barrel.[16] It can use STANAG-adapted magazines.

MA-12

A Myanmar-made light machine gun of the HK33 made under license by KaPaSa in cooperation with Myanmar Fritz Werner Industries alongside engineers from the Electro-Mechanical and Engineering Corps of the Army of Myanmar (EMEC), which had a heavy barrel and bipod with a carry handle. It can use STANAG-adapted magazines.

HK43

Heckler & Koch also manufactured a semi-automatic only variant of the HK33A2 for the civilian market called the Heckler & Koch HK43. The HK40-series was designed for sale to conscripts so they could be familiar with their service rifle before entering military service, then a common practice in Germany and Switzerland. They had a bayonet mount and furniture just like the military model, but came with a semi-auto trigger pack instead of a full auto trigger pack. This allowed a civilian rifle to be easily made into an assault rifle just by dropping in a full auto trigger pack. It would be succeeded by the HK93A2 and its retractable stock version the HK93A3. The HK93 series had a redesigned semi-automatic trigger pack and metal shelf installed in the trigger group well that made it impossible for it to fit a full-auto trigger pack. It also had the bayonet mount removed and had different furniture.C-93Civilian semi-automatic sporting version produced by Century International Arms, Inc. It comes with an 18.9 or 16.25-inch (413 mm) barrel with a 1:9 twist ratio. A carrying handle and 40-round magazine are standard. Advertised weight is 8.2 lbs. The C-93 is built from Thai Type-11 parts kits using an American made barrel and other miscellaneous American parts.