HK53 Assault Rifle and HK53 MICV Assault Rifle

The HK53 Assault Rifle is an HK33 with a greatly abbreviated 8.3-inch barrel. Though the Germans classify the HK53 Assault Rifle as a submachinegun due to its short barrel length, most of the Western world (particularly North and South American countries, as well as the Russians and Chinese) use the newer terms “short assault rifle” or “assault carbine.” Depending on how you look at it, the HK53 Assault Rifle is a vastly scaled-down G-3, a scaled-up MP5 submachinegun, or a compromise between the two.

Original production HK53s used a three-position fire selector (safe, semiautomatic, automatic), but this was quickly replaced with a four position designed specifically for the HK53; though it is a type of flash suppressor it’s highly-effective design makes it function more like a muzzle brake as well as dampening muzzle flash and blast far better than the average flash suppressor (though it is rather larger than the typical assault rifle’s flash suppressor). Provision is made for a wide variety of optical equipment and magazines (most HK-33 or US/NATO magazines may be used). It cannot, however, use rifle grenades or mount a bayonet, and underbarrel grenade launchers which will fit on a standard HK53 Assault Rifle.

HK53 Assault Rifle Standard

The US Navy SEALs were noted users of the HK53 Assault Rifle (as well as the HK33 and HK33K), until the M-4 and its variants became available. Knight Manufacturing has recently introduced an MWS (Modular Weapon System) kit for the HK53 Assault Rifle, consisting of a replacement handguard with three MIL-STD-1913 rails (one on each side of the handguard, and one underneath), a side-mounted optics mount (as the HK53’s charging handle is on the top of the weapon, slightly offset to the left), and a variety of KAC’s standard add-ons.

HK53A3 with old Hensoldt Aiming Point Projector

In 1972, as the vehicle that would eventually become the M-2 Bradley IFV was being developed, the US Army was also looking for a firing port weapon to use with the new vehicle. Among the entries for this competition was Heckler & Koch, and they entered a variant of the HK-53 called the HK53 MICV Assault Rifle. The HK53 MICV Assault Rifle for the most part used a standard HK53 receiver, pistol grip, and mechanism; there were, however, numerous modifications made to the HK53 for the role. The front sight of the HK53 was removed, as were the handguards. The handguards were replaced by a simple ventilated barrel jacket and sleeve equipped with an attachment for the ball-and-socket joint of the US Army’s developmental vehicle (then called the XM-723 MICV).

HK53 MICV Assault Rifle

An attachment point was added to the right side of the receiver, allowing a canvas bag-type brass catcher to be placed over the ejection port. (This brass catcher had the incidental effect of capturing any gasses from the firing of the weapon that didn’t get ventilated outside of the vehicle.) The stock was removed, as was any capacity to mount either a fixed or folding stock, and a simple endcap closed the back of the receiver. Operation of the HK53 Assault Rifle was modified so that the HK53 fired from an open bolt instead of the traditional H&K method of firing from a closed bolt (open-bolt operation allows for better cooling of the barrel and mechanism and made the HK53 Assault Rifle more compatible with the XM-723’s method of venting firing gasses outside of the vehicle).

Finally, the original fire selector mechanism was used, though the cyclic rate of the HK53 was almost doubled. In the end, however, the US Army decided to adopt the Colt M-231 instead; though Heckler & Koch continued to improve and shop around the HK53 MICV Assault Rifle (particularly to the Bundeswehr, who was at the time looking for a firing port weapon for the Marder), the HK53 MICV Assault Rifle eventually became one of those interesting designs that never went into use, and is now a very rare item.