During a discussion at the ADPA show In June, the HK team
suggested that this writer come out to their newest test of the
40mm GMG, a select-fire grenade machine gun. Alluding to a
"torture test," I never dreamed that they also had a torture
test of the participants in mind. Yuma, Arizona in August is
consistently above 110 degrees Farenheit. So, camera and
notebook in hand, I put on my desert hat, dropped into Pheonix,
grabbed a car, and made ready for the appointed day -
Ever since the invention of explosives, men of war have been looking for
new ways to throw "bombs" accurately from a distance. History is filled
with tales of cannon, catapult, mortar, sappers and grenadiers, and many
of the stories are of the mishaps involved. Avoiding "short rounds," "fast
fuses" and "tube bursts" has been a major preoccupation of those who
design and use projected explosives. Mechanical fuses were an innovation
that solved many of the problems, and the newer spin-armed types have
allowed more security to the operators.
Modern armies have many types of weapons at hand. The grenadier of
the 1960s had a dedicated weapon, the M79. In order to make every
grenadier a rifleman as well (and vice versa), the M203 series of launcher
was developed. In a parallel development, Honeywell worked on a
crank-operated 40mm launcher for tripod or patrol boat mount using the
same low-pressure round as the M79. Then there was a helicopter
pod-mounted unit that fired a newer, longer 40mm x 53 round. This new
round had a much longer range than the old one, and it had too much
recoil to be used as a shoulder-fired weapon. Ranges of 2000 meters
were recorded. The U.S. Naval Ordnance project with Colonel George
Chinn produced the MK 19 series of fully automatic grenade machine
guns, and this fine weapon is still in use today, manufactured as the MK
19 Mod 3 by Saco Defense Inc. (See MGN Vol. 8 No. 12, May 1995.)
There is an old expression "close only counts in horseshoes and hand
grenades," which applies to most dual-purpose HE rounds. Machine guns
were originally intended as "area" weapons, not "point" weapons. The
art of machine gunning has suffered greatly with the recent emphasis on
"point" use in the military, which can be traced to doctrine that is geared
more for a belt-fed rifle use than a squad automatic weapon. With the
introduction of the fully automatic grenade machine gun, and their
extended ranges, we give new meaning to the term "area" use.
A grenadier needs to get his grenades within a certain distance of
soldiers (soft targets) in order to inflict casualties. He must also hit
directly on vehicles or bunkers (hard targets) when the shaped charge
aspect of the ammunition is required to penetrate armor. It was with
these two thoughts in mind that this individual participated in the
Yuma tests. I wanted to find out if Heckler and Koch's newest weapon
could perform in both of these diverse roles while standing up to the
desert environment.
MGN photographer Jim Bonis, gunsmith Stan Andrewski and I had torn
the 40mm GMG down to its basic parts at the ADPA show, so I had some
familiarity with the weapon. Heading out to Yuma to go one-on-one
with the actual designers was a special treat; unfortunately, security
only allowed one person to go. (Guess who drew the "short" straw.
Being Technical Editor has its benefits.)
The 40mm GMG was developed at HK GmbH over the last four years,
and the one we tested was prototype serial number 011. It is a
blowback-operated gun. It uses the same feed system as that on
the MG42 and fires from an open breech. The round is stripped from
the belt and moved forward into the chamber. Because of the method
of feeding, the belts of ammunition must be reversed from the U.S. MK19
use - the male end of the link must be presented first. HK has designed
a link that will work in both grenade launchers, and it is waiting for
approval from the manufacturers of ammunition as well as a blessing
from the other end users. Until that point is realized, and all of the
ammunition is standardized, every can that gets opened must have the
belt pulled and reinstalled in reverse.
The Germans had scheduled the test at Yuma Proving Grounds on the
Mexican border in Arizona, where the U.S. Army has extensive testing
facilities. HK had hired the YPG as a sight for their final environmental
testing to meet the German Army's criteria. Winter testing is done in
Northem Europe, of course, but the best desert facility in the world is
at Yuma. Hot, dry, and dusty, YPG is able to assist military testers in
actually putting their products through controlled desert testing, not
merely a simulation. (Unfortunately the testers also achieve the same
reality check. In the 116 degree fahrenheit heat, we grilled lunch on
a wood fire out in the desert - I was thinking about cold cuts and ice
water, but the hot chicken was excellent!)
Ten thousand rounds of exploding target practice ammo needed to be
fired in order to complete the test - at $38 per round, that adds up fairly
quickly. I personally fired over 300 rounds. Ranges varied from 500 to
1500 meters. By choice, I did most of my firing at 1000 meters. As much
fun as this sounds like, if you ask any "tester" he will tell you the same
thing. After a hundred rounds or so, it becomes work - and this was
serious work. HK needed answers on how well their 40 mm GMG would
work.
At 1,000 meters the 10' x 10' plywood target looked extremely small. It
was the kind of target you might use to sight a scoped rifle to center,
then check the group and start getting serious on smaller targets. After
my first couple of rounds dropped short, I got the feel of it and started
seeing white flashes on target every time! This was pretty impressive -
first time on the launcher and dropping them right in! Volker Kurtz,
from HK GmbH remarked that it was a wonderful thing that a novice
such as myself, who had little experience with machine guns and grenade
launchers, could learn so quickly ... but, honestly, this weapon was right
on target. Almost every shot I fired from it, using the reflex sight, went
right into the kill zone. With some more practice, I was pretty confident
that I could place rounds consistently inside a normal window-sized
area. That's not a brag; I was really impressed with the accuracy of
the 40mm GMG. At 1000 yards it was accurate; at 500 yards it was
absolutely zeroed!
Area fire was a little trickier. Every automatic weapon has a natural
cyclic rate - the recoil of the gun, its return, and the bolt travel, combined
with the effect on the operator. With a grenade launcher firing sustained
fire (it's not usually referred to as automatic on these launchers), being
out of sync with that rate can have a drastic effect on where the grenades
land and the size of the group. We do not speak of 4 inch groups
at 800 meters. We think more in terms of 16 meter groups. Once I had
figured out how to "ride" the 40mm GMG, I was very impressed with how
tight the groups were. I could pick an area of brush on the 750 meter
mark and cover it with a 3-second burst. I was done before the first
rounds hit and could sit back and watch the bright flashes of light
saturate the area. These groups were pretty impressive. Again, the
objective is to "cover" an area, not put them all in the same spot.
Keeping the group fairly tight was easy. Indirect fire with a good spotter
would be better than any mortar could dream of being.
The 40mm GMG is significantly lighter than the MK 19 Mod 3. At 29 kg.,
it is 7.5 kg. lighter. As long as the strength and accuracy is there, lighter
is usually better. One of the methods of lightening the design is through
the simplicity of design and manufacture. The receiver is cut from a
one-piece aluminum extrusion instead of being made from welded steel
plates. The bolt is much simpler than the MK 19 as well.
The ease of switching from a left feed to a right feed is illustrated in
the photo sequence [omitted here], but the 40mm GMG always ejects to
the right. Disassembly can be done (and was with me as a witness) in
about 1 1/2 minutes. Putting it back together was just as swift, and no
tools were used other than some of the pins that were taken from the
40mm GMG as part of disassembly.
There were two methods of firing the unit when it was tripod-mounted.
The operator can choose to use the spade grips and a thumb trigger,
which is similar to the M2HBs, or to use the "motorcycle" type grips
that were on the soft mount. I preferred the "motorcycle" grips in
both of the mounts that were available for us to use. The ground
mount was a Norwegian lightweight aluminum unit that worked quite
well when extended properly. The first time I saw it used there was
a lot of "flex" to it, but it had not been properly secured. The other
mount was firing from the Humvee. This was a much more secure
mount, and dialing in fire with the traverse and elevation mechanism
was a cinch - with the reflex sight it was like watching TV! The 40mm
GMG will mount anywhere that the M2HB or MK 19 will.
Safety features are important on most firearms; on a fully automatic
grenade launcher they are absolutely critical. Imagine a round stuck
in the bore, and another round strikes it from behind. Even considering
the spin arm fuze, you have more than a "belled" barrel. HK built in
a number of safety features:
Safety/Fire Selector Lever
The safety/fire selector lever features the settings "Safe," "Single Fire"
and "Sustained Fire." Setting the safety/fire selector lever at "Safe" not
only blocks the trigger mechanism but additionally locks the bolt in its
cocked position.
Loading Safety
By opening the feed cover, the open bolt will automatically be locked
in position, protecting the operator from injuries from an
unintentionally-released and forward-snapping bolt.
Firing Pin Safety
This independent safety system ensures that in any event the firing pin
can only reach the primer after the cartridge has been chambered so far
that the cartridge case is fully supported by the chamber.
Bolt Lock
This mechanically locks the bolt in position and permits the operator
to clear the Grenade Machine Gun safely without fear of bolt movement.
Cocking Safety
In case the gunner fails to pull back the bolt completely and releases
the cocking handle before the bolt has been engaged in its cocked
position, an integral automatic mechanism prevents the bolt from traveling
forward and accidentally firing.
All things considered, the HK 40mm GMG is now "the contender"; no
question about it. Saco Defense is rumored to have a new lightweight
MK 19, but this author has not had a chance to look it over. The lightweight
40mm GMG is an accurate, effective, well-designed weapon. The innovation
of design should help to keep the manufacturing costs down and make this
a very competitive design.
Note: HK does not want any contact from non-military or unqualified
end-users regarding the 40mm GMG. Military Procurement may contact:
Wayne Weber, HK Inc. Sterling, VA. (703) 450-1900.
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