The HK33 Rifle Never Really Caught On
But the shorter HK53 was more popular
In 1968 Heckler & Koch launched the HK33 rifle, chambered in 5.56-by-45 millimeter, to compete with Colt’s AR-15/M16. The HK33, and later HK53, used the same roller-delayed blowback action the company developed for the 7.62-by-51-millimeter G3 in the mid-1950s.
The HK33 won only a few major contracts. For its part, the German military opted to continue using the G3.
The HK33 boasted a modular design. Users could replace the butt of the standard rifle with a collapsible telescopic metal stock. H&K also designed a carbine version of the full-length HK33, the HK33K, which featured a telescopic metal stock and 12.7-inch barrel. In the mid-1970s H&K began development of an even shorter version.
The result was essentially an intermediate-caliber submachine gun similar to the Colt Commando and the Soviet AKS-74U. H&K designated this new weapon the HK53. It had the same telescopic stock as the HK33K and MP5 and an 11-inch barrel. The HK53 had a polymer forearm similar to the MP5’s.
Like the HK33, the HK53 fed from 25-, 30- or 40-round box magazines. The weapon weighed 6.6 pounds, around two pounds less than its parent rifle the HK33. Unlike the HK33, the HK53 had a four-prong flash-hider.
Several police forces and militaries adopted the HK53. It was popular in Latin America and Asia. The British Special Air Service and Royal Marines issued it as the L101A1.
Due to its short length, the HK53 found itself pressed into the port-firing role — that is, for use by infantry firing out through tiny gaps in the hulls of armored vehicles. In this role, the foregrip and stock was removed and a specially-designed end-cap and a spent-case bag could be attached.
During its service life, the HK53 went through a series of changes to furniture moldings, buttstock types and fire-selector options. It remained in production into the early 2000s when Heckler & Koch finally replaced the HK33 and HK53 with the G36 and G36K, respectively.