Belt-fed machine guns have played an important role in
nearly every major military battle since the "War to End
All Wars", World War I. Across the open fields of France
in "no man's land", belt-fed machine guns commanded
the flow of battle and were always the focal point of
attacking forces within the defensive lines of their enemy.
The utter devestation of sustained, full-power rifle caliber
automatic fire against attacking infantry is well-known
and still every bit a lethal today even with all of our
many technological advances in individual weapons and
World War II proved that the belt-fed machine gun had
successfully progressed into the "light machine gun" role
allowing the gun to be carried easily by one "shooter"
during the assault. The use of air-cooled versus
water-cooled sustainment methods, lighter yet stronger
materials and designs, more streamlined weapons employing
bipods, assault slings, belt boxes and drums made the
belt-fed machine gun mobile without lessening its lethality.
The frightening target effects of the heavy machine
guns of World War I, like the Vickers, Maxim and Browning
guns had not changed. The weapons designers of the
world had simply designed into the lighter, smaller
weapons all of the capabilities of the heavy machine
guns but with new enhancements to make them even
more lethal than their more bulky predecessors.
The world learned very quickly to respect the German
MG34 and MG42 machine guns for their high rates of fire
and almost assured lethality of anyone seen through the
gunners sights. The MG34 and MG42 are generally recognized
as the earliest successful exapmles of a true "General
Purpose Machine Gun" (GPMG). GPMG's are commonly
defined as guns that can be used effectively by a lone
gunner in the light assault role from the shoulder, assault
firing position or from the prone position using a light bipod.
By placing these same weapons onto field tripods, fixed
or vehicular mounts the GPMG serves well in the role of
a medium machine gun serviced by a crew for defensive,
sustained fire engagement.
During World War 11 the Germans favored high rates of
fire in their machine guns for numerous reasons, not
excluding the bone chilling psychological effects on the
enemy. German designers believed, and it was well proven
in actual combat, that a higher rate of fire would saturate
the beaten zone produced by the weapon down range with
more projectiles. On an enemy squad in the open for example,
this would increase the probability that any personnel within
this area would be hit before they could "go to ground"
and seek cover after the initial engagement.
Anyone who has seen the recent film "Saving Private Ryan"
can better appreciate the abilities of a machine gun like the
MG42 in competent hands. Referred to as "Hitler's chain saw",
the report of the MG42 with it's 1,200 - 1,400 cyclic rate
of fire was often described as sounding like the tearing
of canvas. That sound, and the guns immense capability
for suppressive fire both in the defensive role and during
the assault, were feared in its day and are still revered in
modern times by many who believe the MG42 to be one of
the worlds best all-around belt-fed machine guns. In fact,
the MG42 is still used by the German Bundeswehr today as
the MG3 chambered for the 7.62x51 mm NATO cartridge.
The attributes of all of today's successful belt-fed GPMG's
are similar. Lightweight (generally under 26 pounds),
man-portable and sustainable by a single operator with
quick change barrels for sustained fire and a bipod and
buttstock for assault firing. Beyond these common
attributes, the designs, features, accessories, methods
of operation, reliability and performance vary wildly.
Without question, one of the worlds best though severely
underrated GPMG's is the 7.62x511 mm NATO caliber HK21E
Machine Gun from Heckler & Koch. To many, the HK21E is
without question the world's most flexible weapon of its
type, offering its users features and capabilities not
available in competing designs. It is for this reason that
the special units in the world that understand and appreciate
the unique capabilities of the HK21E have selected it for
use in both classic machine gun roles and for military and
law enforcement special applications.
The HK21E (E for "Export") is a true lightweight,
general-purpose machine gun in caliber 7.62x51mm NATO.
The HK21E can be fired from a tripod, bipod or from the
shoulder. In the belt-fed configuration fitted with a 22-inch
barrel, the weapon weighs just over 20 pounds with the
bipod, unloaded. With the 17.7 inch barrel installed the
HK21E weighs in at 19.40 pounds and at 17.96 pounds
without bipod. Detailed specifications for the HK21E and
its many modular variations are included [below].
Some may remember the less-than stellar long-term
performance of the first belt-fed HK machine gun, the
HK21. Little more than an HK 7.62mm G3 assault rifle
with a belt feed mechanism added to feed the weapon,
early HK21s and later the improved HK21A1 models found
favor with many Armies around the world. Some of
the current users of the HK21E machine gun and its
numerous variants include the armies of Thailand, Peru,
Mexico, Finland, Ecuador and many others too numerous
to mention here. Even special units like the U.S. Army's
elite Delta Force used the early model of the HK21 during
the attempt to rescue the American hostages in Iran in
1980 during Operation Eagle Claw. Today various U.S.
special operations units and federal law enforcement
agencies as well as security elements within the
Department of Energy use HK21Es.
However, early HK21s were not without their problems
and in many ways could be described as immature in their
design. The early prototype 5.56x45mm NATO HK23s,
basically HK21s fitted with 5.56mm bolt, barrel and feed
unit, submitted to the U.S. Army for testing as the XM262
candidate for the Army's SAW trials performed poorly.
At the end the Army's testing, the HK gun was surpassed
by the performance of the FN MINIMI which was ultimately
selected and fielded within the U.S. military as the M249.
Exposure of many to "converted" HK21's built by American
Class II manufacturers from semi-automatic HK91 assault
rifles or the inferior HK21s built by HK licensed plants
throughout the world did little to improve the collective
admiration of the HK21 design.
Parts breakages, buffer problems and other weak points
in the early HK21 and HK23 models resulted in almost
continuous improvements in the design, throughout the
life span of the HK21 and HK21A1 and finally into the
current model today known as the HK21E. In the E model,
the length of the receiver was increased by a full inch
to provide additional recoil length for the bolt group.
Reinforcing bars were added to the receiver to provide
additional strength and rigidity. The bolt head, extractor
and locking roller holder were completely redesigned
as were the bolt carrier and recoil spring assembly,
belt feed unit, buffer, barrel and trigger group. Little
remains unchanged in the design or performance of the
HK21E from its earlier iterations.
During its 35+ years of life, many variants to the basic
weapon have been produced, primarily due to the HK21's
unique modular design, typical of the HK family of weapons.
A simple swap of the barrel, feed unit and bolt group
allows the weapon to be converted in any one of three
calibers to include 7.62x51mm NATO, 5.56x45mm NATO
and even 7.62x39mm Russian in a model never produced
called the HK22A1. This caliber conversion of the HK21
can easily be accomplished by the operator without tools,
in a matter of seconds. Simple conversion from belt to
box magazine or drum feed is also possible at operator
level in the field. There were even plans at HK for a
.50 BMG caliber HK25 machine gun, a gun that by all
accounts never progressed beyond an advertisement
that once appeared in an HK catalog.
HK21Es imported into the U.S. prior to 1995 would function
with disintegrating M13 or DM6 link belts or the continuous
German DM1 belts without adjustment. In 1995 HK redesigned
the belt feed units and bolt heads of the HK21 E to optimize
the reliability of the weapon when using belts assembled
with U.S. M13 links. As the pitch or distance between the
M13/DM6 and DM1 links varies, HK21Es produced after 1995
are no longer designed to work reliably with continuous,
non-disintegrating DM1 belts, though HK21Es can be special
ordered for use with these belts. A true series production
caliber and feed convertible general-purpose machine gun,
the HK21E is unique in the history of the breed. Even today
the truly modern HK2 E machine gun can still be fitted with
caliber and feed conversion kits that allow for flexibility
unheard of in competing designs. The component parts
that need to be exchanged to effect these conversions
are listed in the specification table on page 50.
What is it that reputedly makes the HK21E so superior
to other designs? As is often the case with successful
products there is no single feature that reserves its place
in the history books. With the HK21E its unmatched
capabilities come from its combination of unparalleled
flexibility, features and uncompromising performance.
The HK21's closed bolt operation and free-floating barrel
provide excellent accuracy like that of a sniper rifle.
While many rightly contend that historically a machine
gun has been an area fire, suppressive weapon, the HK21E
with its cyclic rate of fire of 800 rounds per minute (13
rounds per second) can definitely suppress a target area.
However, the superior accuracy, which its design brings
to the user, allows it to be used in ways and in roles never
before envisioned for a machine gun. For example, HK21E's
are used by the German Border Guard in a 7.62mm box
magazine-fed version called the G8 Rifle. Employing a
special 50-round drum magazine and telescopic sight, the
G8 is used in a paramilitary/law enforcement role as a light
support weapon when highly accurate, surgical or suppressive
fire is required against vehicular, aircraft or massed personnel
The HK21E, or its box magazine-fed variants, is often used
in conjunction with or in place of a sniper rifle for precision
long-range engagements across the full target spectrum.
Its capabilities allow it to be used to engage single personnel
targets, to accurately mark targets for other weapons, to
disable vehicles or equipment, or for any task where the
capabilities of putting .30 caliber slugs onto or through a
target with repeatable accuracy is required. The HK21E
can easily accomplish this task and, unlike the fully automatic
fire from a conventional machine gun, without creating the
liability of rounds that miss the intended target and could
cause unwanted collateral damage to surrounding personnel
Even firing belted military ball ammunition using iron sights,
HK21Es regularly will shoot sub-MOA groups at almost any
range. Three-shot groups measuring .75 inches at 100 meters
are well within this machine guns capabilities when fired from
a bipod supported prone firing position. This level of accuracy
opens the door for the users of the HK21E to engage pinpoint
targets with accurate, effective semi-automatic fire precluding
the need to waste precious ammunition in the sustained fire
mode. If necessary, as the tactical situation demands, a simple
flick of the safety/selector lever will allow that same shooter
to "hose down" targets with sustainable automatic fire. This
unique capability is not an HK "sales pitch" that is promoted
and never used in the "real world". This capability is available
only in the HK21E and is one that is being used every day by
military and law enforcement units around the world.
An ambidextrous 4-position trigger group with semi-automatic,
3-round burst and fully automatic modes of fire and "pictogram"
markings (HK's unique and universally understood colored
bullet symbols) for the modes of fire are standard on the
HK21E. Few machineguns offer other than the fully automatic
mode of fire or safety/selector levers for left-hand firing
though these features are often used by the HK21E gunner
during normal training and deployment.
Like the German MG42 and MG3 machine guns, the HK21E
provides the user with a simple, quick-change barrel capability.
The HK design takes the simplicity and ease of the barrel
exchange to new heights of simplicity. To change the barrel
of the HK21E the bolt is locked open, the barrel release lever
depressed with the thumb and the barrel rotated 35 degrees
and removed rearward from the weapon using only one hand.
This procedure can be easily accomplished even after firing
1,000 rounds, as the well-insulated barrel handle precludes
the need for an asbestos glove, as with many other machine
gun designs. A special insulated spare barrel carrier is offered
for the HK machine guns that allows a scalding hot barrel
slung across the shoulder to be safely carried by a member
of the gun crew. The layout of the HK21E allows the gunner
the means to easily change the barrel with one hand, in the
prone without the need to break out of the firing position
or expose himself unnecessarily to unwelcome enemy
observation or fire.
Unlike the American M60 and FN MAG58 (known in the U.S.
as the M240) machine guns, only the barrel of the HK21E
is removed during barrel changes. There is no bipod, gas
system, carrying handle or front sight attached to the barrel.
This well thought out and executed arrangement simplifies
and speeds barrel changes from all firing positions and all
but eliminates any change in zero of the weapon from barrel
to barrel. This design also reduces the total weight of the
machine gun crew's load as spare barrels are carried free
from attached bipods and gas systems that add to the weight
of competing designs. Without a gas system and its required
gas port, the structural integrity of the cold hammer forged
HK21E barrel is not compromised.
Anyone who has attempted to change a hot barrel on an
M60 from a prone position when firing off the bipod can
attest to the complexity of this procedure. Lift and hold
the gun off of the bipod to free the barrel, disengage the
barrel latch, don your asbestos glove, remove the hot barrel
(remember not to lay the hot barrel on the spare barrel bag
or it will melt through the bag), insert the new barrel and
align the gas piston, fully seat the barrel in the receiver
and hold it in place while you engage the barrel latch. None
of this is required with the HK21E.
The HK21E provides the operator with a forward assist for
silent loading or to help chamber a round due to improper
loading procedure, such as riding the cocking lever forward.
The receiver of the HK21E has a guaranteed 60,000 round
minimum service life. Barrels regularly withstand the firing
of 40,000 rounds or more with no sign of accuracy degradation,
even after being abused by long bursts of uninterrupted
automatic fire. A removable folding carrying handle on
the receiver, used most often to lift the weapon from the
ground as the gunner rushes forward, is positioned at the
weapon's balance point and folds out of the way when
not being used. The HK21E provides a cook-off rate in
excess of 1,000 rounds (cyclic), a fact proven by extensive
testing, despite some claims that this is impossible from a
closed-bolt design like the HK21E.
Removable belt boxes can be used to hold 100 rounds of
7.62x51 mm NATO on the HK21E for firing from vehicles or
during the assault. Special belt starter tabs allow the weapon
to be loaded with the bolt open or closed and with the belt
feed unit locked in the normal firing position. A quick drag
of the belt through the unique ratchet drive wheel arrangement
of the HK21E's belt feed unit using the belt starter tab places
the belt in the position for loading. Retracting and releasing
the cocking lever chambers the first round and prepares
the weapon for firing.
It is possible with the HK21E to actuate the cocking lever
and bolt of the weapon while the safety/selector lever
remains in the safe position, a safety feature not available
on many machine guns. "Run away" firing wherein the gun
continues firing after the trigger is released (dangerous and
not uncommon in the M60 due to it's simple but unreliable
sear/operating rod design), is unlikely in the HK21E due
to the unique design of the gun's trigger mechanism.
The weapon is of a closed-bolt design and is delayed
blow-back operated using the classic HK roller-locked bolt
to delay the opening of the breech. With the fluted chamber
common in many HK weapons, the cartridge case actually
pushes itself from the chamber, insuring positive extraction
and ejection even under the most inhospitable environmental
conditions. In most gas-operated machine guns the empty
cartridge case is pulled from the chamber by the bolt as it
is driven rearward by the gas system. Should the extractor
or extractor spring of the gas-operated machine gun fail,
the spent case may well remain in the weapon causing a
stoppage. Unlike gas-operated machine guns (such as the
FN MAG58) in the HK21E there is no need for a gas regulator
to adjust the gas flow into the system to account for sluggish
operation due to fouling in the weapon. In fact, there is
no gas system in the HK21E at all to be maintained. The
cyclic rate of fire of the HK21E decreases in cadence to
700 rounds per minute when the weapon is converted to
any one of the box magazine-fed variants.
The HK21E is unique in its modular approach. Each of
the assembly groups of the weapon can be removed in
seconds by the operator without tools. This allows the
configuration of the HK21E to be "tailored" to meet the
specific operational needs of the operator. Maintenance
is also simplified with the HK21E, as all of the modular
assembly groups and individual parts of the weapon are
100% interchangeable without the need for hand fitting.
Damaged or unserviceable assembly groups can simply
be exchanged by the operator with a new one and fixed
by an armorer when the opportunity allows, without
having to pull the complete weapon out of service.
Like all HK weapons, the HK21E is simple and quick
to field strip and reassemble and requires no tools
to accomplish this. The removable assembly group
construction and accessibility to the breech area in
the HK21E receiver makes for quick and easy cleaning.
The iron sights of the HK21E are of the classic style
found on most HK long guns. The front sight post is
protected by circular hood that is in fact an integral
component of sight alignment with the rear "peep"
aperture. The rear sight offers external knobs for
elevation and windage adjustment to ranges matching
the 1,200 meter maximum effective range of the weapon.
The rear sight provides a means to zero the weapon
independent of the external adjustment knob settings
using a simple Philips head screwdriver.
The HK Export model machine guns have a well thought
out quick-detachable sight mounting system that provides
100 percent retum-to-zero capability for all types of
targeting devices including telescopic and reflex sights
and visible or IR laser aimers. This system is used on HK
sniper rifles and provides sub-minute of angle accuracy,
even from the HK21E. It allows various types of targeting
devices to be interchanged on the weapon with the
assurance that the zero will remain unaffected even
after repeated mounting and dismounting. This sight
mounting system allows the standard iron sights and
optional targeting devices to be mounted in tandem
on the weapon. The special box magazine-fed light
machine gun version of the HK21E used with a telescopic
sight by the German Border Guard unit GSG-9 as a
light support weapon provides excellent accuracy
approaching or even exceeding that of many precision
As an example of the weapon's incredible performance,
many public live-fire demonstrations have been conducted
by HK, each year in fact at the annual Small Arms Division
meeting of the American Defense Preparedness Association
(ADPA, now NDIA). HK demonstrators prove the reliability
of the HK21E by firing a single continuous 500 or even
1,000-round belt in the fully automatic mode of fire without
interruption. During this firing the unique feed system of
the HK21E drags the 32-foot long, 25 pound 500-round belt
along the ground and up into the weapon without assistance
from the gunner or assistant gunner. Immediately upon
completion of firing the barrel is removed from the weapon
and held by the shooter in his bare hand to illustrate the
advantages of the HK21Es quick-change barrel system.
The barrel, hot enough to easily light a cigarette on, is
dunked in water to return it to the ambient temperature
and reinstalled in the weapon. Afterwards, the gun is
placed in the semi-automatic mode of fire and then used
to accurately and easily engage 3-inch targets at ranges
up to and including 300 meters in rapid-fire cadence. This
same barrel can and will be used time and time again in
other similar demonstrations due to the quality of the
materials and the cold hammer forging production process
used during its manufacture.
The HK21E can also pull a free hanging belt longer than
7 feet in length into the weapon during firing without
assistance, a mark of excellent belt pull and reliability,
a characteristic especially appreciated in less than ideal
Often times the demonstrator will convert the weapon
from caliber to caliber and from box feed to belt feed
and back in under a minute without tools as the crowd
looks on, finishing each manipulation by firing a box, drum
or belt of ammunition to demonstrate the weapon's proper
function. This kind of performance is typical of that which
has made the HK21E appreciated by those who know machine
guns. The standard U.S. military published price for the HK21E
complete with 22.0 or 17.7 inch barrel, detachable bipod with
adjustable folding legs, assault grip, carrying handle, pistol
grip cleaning kit, plastic muzzle cap, a combat carrying sling
and operators manual is @ $4,600 U.S. This price is comparable
to or less than many competing designs that offer far less
in the way of performance and features than those offered
as standard on the HK21E.
Accessories and mounts for the HK21E are endless and
are listed within the enclosed specification table. New
accessories being developed for the HK21E include adapters
to allow for the use of ammunition packaged in cloth U.S.
M60 100-round bandoleers, belt box carrying pouches, multiple
MIL-STND-1913 (Picatinny) Rail sections for attachment
to the weapon's scope mount and receiver, a special helicopter
firing platform, a cartridge case deflector with detachable
collection bag, extended safety/selector levers and even
screw-on sound suppressors for the weapon.
The preceding leads to the obvious question "If the HK21E
is so good, so superior to other machine guns, then why
is it not used by the American military in other than a
few select special units?" This question is actually quite
easy to address. A common phrase "The logistical tail
wags the operational dog" applies in this case. Often
times throughout history the infantry has asked for proven,
superior weapons available off the shelf to carry the fight
to the enemy yet were denied them due to the intervention
of influential factors associated with the logistical support
for the weapon. Through the last half of the 1800's the
single-shot U.S. Springfield Trapdoor rifle remained in service
with American infantry even though the superiority of
repeating weapons like the Henry, Spencer, Winchester
and other rifles had been proven, demonstrated in battle
and requested by unit commanders, and even approved
by the U.S. President himself. Managers of the armories
where the Trapdoor rifles were made, seemingly more
concerned with their positions and jobs than the lives
of the combat soldiers carrying the weapons into battle,
used their political influence from within the logistical
system to delay and even prevent the issue of superior
weapons available in that day. This is only one example;
there were many others.
In the United States, the M60 was developed within our
national armory system. American armory designers
made use of existing design features from various weapons,
many of them WWII German machine guns, and combined
these features into what should have been a superior
weapon. In the eyes of many, however, the M60 was
and still is today disturbingly inferior in countless ways
to the German guns that had come decades before the
M60, and in the case of the HK21E decades after. Yet
with all of its shortcomings the M60 and its E3 variant
remain in service today within the U.S. Navy and Air Force.
However, the U.S. Army, the Marine Corps and various
special operations groups have seen the light and within
the past five years have replaced almost all of their M60s
with a ground model of the FN M240 machine gun (called
the M240G in the Marine Corps, the M240B in the U.S. Army).
While this gun is far superior to the M60 in the minds of
many informed individuals, its selection to replace the
tired old M60 was not made simply on its own merit.
For many years the Marine Corps was dissatisfied with
the reliability of the M60. During the 1980's it became
aware that the Army had in its war stock a large surplus
of new, unissued M240 machine guns that had been
purchased for use on the M1A1 tank. These guns were
made available to the Marines who, with the help of
FNMI, quickly developed a ground modification kit to
allow the weapons to be used as a GPMG in place of
the M60E3s then fielded in the Corps. Though weighing
nearly 26 pounds, some three or more pounds heavier
than the new improved M60E4, test sample of the M240E4
proved to be far more reliable than those of the M60E4
in extensive firing tests and was thus selected for issue
within the Marine Corps.
Based on the finding of the Marine Corps tests, the U.S.
Army has since replaced all of the M60s within units like
the 82nd Airborne Division, the Ranger Regiment and other
conventional infantry and special operations units with the
M240B. The Army's version of the M240 differs slightly from
the Corps version and weighs approximately 28 pounds.
In the case of the Army's decision to field the M240B to
replace the M60, they did for a short time consider conducting
a side-by-side comparative test that was also to include
the lighter HK21E. This was the point where the logistical
tail wagged the operational dog. The HK21E was never
tested by the U.S. Army against the M60E4 and M240E4
because "it was not in or supported by the U.S. Government
supply system". Try explaining this to the grunt carrying
the M240B or G model, an admittedly excellent 26 to 28
pound weapon but one designed in 1958 and without
any of the many desirable features found on the HK21E.
With all of the equipment that makes up the infantryman's
current minimum combat load which can often exceed
100 pounds or more, instead of issuing a new machine
gun that was lighter than the 23 pound M60E3, we issued
him one that was actually three to five pounds heavier.
(This was done without considering the fact that there
are lighter machine guns available off the shelf with
a proven record of performance that would preclude
the need to spend precious R&D dollars, like the 18
pound HK21E). Eight full pounds, the difference in
weight between the M240G and the HK21E, nearly one
tenth of his total 100-pound combat load, or 125 rounds
of belted 7.62x51 mm NATO ammunition is a significant
difference one that could decide mission success or
failure. For those special units who can afford to and
are able to buy the best available weapons to get the
job done, the HK21E is very often their first choice.
What is it like to shoot the HK21E? From the classic
light machine gun, bipod supported position the weapon
handles like a slightly bulky semi-automatic rifle on a
bipod. The weapon is normally loaded in the "cleared"
condition: safety on, bolt locked open. The belt is laid
across the belt feed unit against the cartridge stop with
the open side of the links facing up. Unlike the M60
where the bolt travels below the feed cover, the bolt
of the HK21E rides over the belt feed unit and thus the
open side of the links must face the bolt so that the
cartridges can be stripped from it. The cover to the belt
feed unit is then locked in place to secure the belt. The
belt feed unit is then pivoted up and locked in place on
the receiver. If belt starter tabs are available, the belt
can simply be pulled through the belt feed unit with it
in the normal firing position. Of course, the HK21E fires
standard 7.62x51 mm NATO ammunition assembled with
American M13 or German DM6 disintegrating links.
The HK21E is also compatible with special purpose
ammunition to include match, special ball, armor piercing,
visible and IR tracer. From this point once the belt
is inserted the cocking lever is then released with a
practiced slap of the non-firing hand and a round is
The actuation of the firing controls of the HK21E, the
use of the sights and firing are just like that of most
other HK weapons, a distinct advantage from the
training aspect of the operator. In the small arms
currently in the U.S. inventory with the exception of
the M16 rifle and M4 carbine there is no similarity
between the operating controls of the weapons; each
one is different. The HK weapons "system" reduces
training time and increases the familiarity of the operator
with all of the weapons in the inventory, whether it
be a rifle, submachine gun, sniper rifle or machine gun.
A good firing position from the bipod can be improved
by placing the feet of the bipod well into the ground
or against support, such as the edge of a pavement,
windowsill or fighting position. With the rubber buttstock
of the weapon in his shoulder the gunner slides his body
forward against the fixed bipod.
This creates a rock solid and stable firing position that
is undisturbed by even prolonged bursts of automatic
fire. Even inexperienced gunners find it easy to get
two or even three hits on an E-type kneeling silhouette
at 100 yards when firing in the three-round burst mode
from this position. The gunner's non-firing hand grasps
the toe of the buttstock and holds it securely into his
shoulder pocket. The design of the bipod allows for
a limited amount of left to right traverse of the weapon
without moving the placement of the bipod's feet.
The elevation adjustment required to get the sights
on target requires only a slight shift forward or backward
of the shooters body. The gunner makes firm contact
with his or her cheek against the comb of the buttstock.
This brings the rear and front sights into easy alignment.
Centering the circle created by the front sight hood
within the rear sight aperture, by intended design a
skill almost naturally accomplished by the eye and
brain, automatically aligns the sights. The front sight
post is then simply placed on the target at the desired
point-of-impact. A quick adjustment of the non-firing
hand (always free to manipulate the controls of the
weapon while in a firing position, an HK trademark)
to the elevation adjustment knob corrects the sight
setting for the estimated range to the target. The
gunner is now ready to "smoke" the target. Rotate
the combined safety/selector lever into one of three
available modes of fire. 7 to 11 pounds of constant
rearward pressure applied to the trigger will release
the hammer from the sear and fire the weapon. The
design of the HK21E's trigger group insures that the
hammer will not release if the weapon is handled
roughly or dropped from a height of up to 2 meters
with safety/selector set in the safe or fire positions.
Recoil of the HK21E is most often described as mild,
less than that of HK assault rifles of the same caliber,
mainly due to the weight of the weapon in comparison
to that of a rifle, its enhanced spring buffer and the
solid, bipod-supported position described above.
In the 3-round burst mode, the three rounds are fired
quickly enough that a clear vision of the sight picture
as seen before the first round is fired is still visible to
the shooter when the weapon stops firing. Unlike the
3-round burst mode of the M16A2 rifle, there is no
memory in the HK burst device so the weapon wiII
always respond with a full three rounds each time
the trigger is pulled and held to the rear, regardless
of how many rounds were fired during the previous
It is in the fully automatic mode of fire, represented
on the HK21E trigger group as seven little red bullets
in a red box with an open-end meaning "infinite", that
you know you are firing a belt-fed weapon. Short six
to nine round bursts are most effective from the
bipod-supported position. As is the case in most
machine guns fired from the ground, after the second
or third shot the gunners view through the sights is
obscured by the smoke and dust created from the muzzle
blast of the weapon. This is where the eyes of the
assistant gunner to help direct the gunner's aim pays
large dividends in hits on target.
There are the telltale signatures, sounds and sights
common in all guns and unique to each specific model.
Like the sound of the buffer recoiling through the
buffer spring and housing in the buttstock of an M1/AR15,
the HK21E is not without its own unique character.
The high rate of fire is felt in the shoulder as a mild
whack as the bolt group meets the waiting spring buffer
in the buttstock. At 800 rounds per minute, the visual
signature of the weapon comes mainly from the brass
colored "stream" of empty cartridge cases being ejected
from the weapon to the right and forward of the firing
position. Expended links form a tidy pile below and
to the right of the belt feed unit. Violent is one word
often used to describe the ejection pattern of the HK21E.
Cases are thrown 25 feet or more from the weapon
due to the blow-back operating principle unique to the
HK weapon. The always-unpopular police call of empty
brass on the range can be reduced or even eliminated
by an experienced gunner by the careful selection of
a firing point for the HK21E so that the empty cases land
in an area not included in the clean up! A cartridge case
deflector with detachable collection bag is available for
the HK21E and is popular in roles where ejected cases pose
a serious threat to the well being of the shooter, especially
a shooter firing from a helicopter in flight. 7.62mm brass
does not mix well with rotor and turbine blades common
in today's modern helicopters.
The gunner can make barrel changes while still in the prone
position and without the burns often received from less
user-friendly weapons. Barrel changes in the HK21E can
only be made with the bolt locked rearward and thus the
weapon in a "cleared" condition, an additional safety
feature of the gun.
When firing in the assault mode from a standing or hip firing
position, a few select accessories are desirable and in fact
come with the weapon. The detachable assault grip can
be fitted without tools in seconds to one of the many slots
in the barrel casing. Right handed gunners usually prefer
it positioned at about the 7 o'clock position midway along
the barrel casing below the cocking lever's "rest" position.
The adjustable cotton web sling attaches to the sling mounting
points on the left side of the weapon and is slung over the
shooter's head and under his firing ann. The gunner may
then adjust the size of the loop so that the sling is pulled
tightjust as the elbow of the non-firing arm is locked out.
With the gunner assuming an aggressive "fighter's" stance,
the control of this relatively lightweight 18 pound 7.62mm
machine gun, even in long sustained fire bursts at 800 rounds
per minute, is impressive, especially in the hands of an
experienced HK21E gunner. For more accurate aimed fire,
the HK21E can be raised to and fired from the shoulder using
the sights of the weapon as a rifle might be.
Firing the HK21E from one of the many available tripod or
fixed mounts is generally just a matter of aligning the sights
and pulling the trigger. The unique buffered mounts offered
for HK machine guns remove most of the vibration and recoil
from the weapon normally imparted to the shooter, improving
hit probability. "Soft mounts" with integral recoil buffers are
relatively new developments in U.S. military mounts more
common within the past 5 to 10 years. HK mounts have
always included this useful feature, like the WWI and WWII
German mounts that came before them. The HK mounts
designed for anti-aircraft use include the unique "free-aiming"
feature wherein the weight of the gun is supported by the
mount itself to ease aiming and firing at fast moving targets.
After firing, the gun is "cleared", the last link or two is
removed from the belt feed unit and the hits on the target
can be assessed. If everything was done correctly the target
should be showing signs of the serious damage that only a
belt-fed machine gun can inflict.
There is a great deal more to the HK21E machine gun than
meets the eye. It is certainly a machine gun that, when
compared to even more modern designs, has a lot going
for it. Users who have experienced the HK21E know that
it offers unmatched tactical flexibility in a lightweight,
reliable design, with mission capability second to none.