The HK21: Heckler & Koch’s Modular Machine Gun Platform

Since World War 2, militaries around the world understood that their troops needed a squad automatic weapon (SAW).  Here in the modern United States Army, we utilize the FN M249 and will soon progress to the Sig Sauer M250.  Many firearm companies all jumped on this need and developed a myriad of options that would fulfill this role.  This is where the HK21 comes in.

Hechler & Koch (HK), at least in this author’s opinion, is one of the best firearm manufacturers in the world.  Since their inception in 1949 they have constantly pushed firearm design forward.  Their first big break came in 1956 when they were awarded the Bundeswehr (German Army) contract for the G3 Rifle.  Almost immediately they realized they needed a light machine gun to go with their new battle rifle.            

However, the Bundeswehr were not really interested in a light machine gun option.  They were quite happy with the MG3 machine gun.  This design based on the German MG42 from World War 2, was robust and reliable.  However, HK saw the need for nonwestern countries and smaller countries that lacked the ability to develop weapons of their own.  They started work on developing a G3 complement that would be belt fed for these types of countries.          

They would take the roller-delayed blowback mechanism from the G3 (this would be utilized in many HK designs) and “scaled up” the rifle to be a belt-fed machine gun.  In 1961 the HK21 would go into production just 5 years after the G3 rifle, a relatively quick development.  Some of the major changes to the HK21 from the G3 is the receiver.  The HK21 receiver was extended to help with recoil.  It also features a front bipod to assist when firing from the prone position.

Another major change was the fire rate.  The HK G3 fire rate in full auto is around 500-600 rounds a minute.  Powerful, but still fairly controllable in full auto considering both of these guns are chambered in the 7.62 NATO cartridge.  The HK21 has a blistering 800-900 rounds a minute rate of fire.  This does allow it to serve its purpose of supporting and suppressing fire within a squad.  It does greatly increase the recoil.

The gun has seen service in some of histories historic battles middle to end of the 20^th Century.  It has seen service and several nations including Mexico and Greece.  Germany, however, would only very lightly utilize this weapon system.  As mentioned before they were happy with the MG3 and now the MG4 Light Machine Gun (LMG) that is currently being utilized by their forces.

In the United States, we would see use of this weapon platform in the 1980’s by Delta Force and Navy Seals as they searched for a lighter upgrade to the M60 for their SAW.  This would ultimately be replaced by the M249 by the 1990s.  The HK21 would see some very light use during the failed Operation Eagle Claw in an attempt to rescue the Iranian Hostages.

In the end, the HK21 is still a relevant and reliable Squad Automatic Weapon to this day.  It had gone through several upgrades since its inception in 1961 and seems destined for service well into the future.  While never official adopted by a large Western Country, it still serves a need among those countries that cannot produce weapons such as this themselves. Ian McCollum has an excellent video breaking down the disassembly of this weapon.

Here at 2 If By Sea Tactical we strive to bring you the best experience in the firearms world.  As we continue to grow the media arm of 2 If By Sea, make sure you keep tuning in to our Youtube Channel @2ifbyseatactical and right here at “The Patriot’s Almanac” to stay informed on the latest happenings in the firearm world! But we are not lawyers, so this isn't legal guidance.

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