Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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.338 MG   Army Guns 20+mm

Started by autogun; 4068 views.

From: autogun


OK, now it can be told. GD-ATP has announced at NDIA a new belt-fed LWMMG (lightweight medium machine gun) in .338 calibre.

The gun is based on the design of the XM806 .50 LWMG, and uses the same soft recoil design which fires as the barrel group is moving forward. This smoothes out the recoil pulses and also slows the rate of fire to 500 rpm. It has a quick-change barrel with fixed headspace. This design means that the gun weight is kept down to just 24 lbs. It can fit on the M192 tripod.

One unexpected twist is that the gun is chambered in .338 Norma Magnum, not .338 Lapua Magnum. The Norma case is based on the Lapua's, but is slightly shorter so that longer, heavier, low-drag bullets can be used while keeping the overall cartridge length the same as the Lapua's. The new MG fires a 300 grain bullet at 2,650 fps from a 24 inch barrel. Effective range is said to be 1,700 m (which seems reasonable).

Any existing .338 LM bolt action rifles can easily be rechambered to .338 NM by switching the barrel.

It will be very interesting to see if this catches on.



From: H_Minus


Very nice IMO!  This could replace all vehicle mounted 7.62mm NATO GPMGs eventually, and could replace some 7.62mm NATO GPMGs and .50 cal M2 HMGs in dismounted infantry Bn's.  It's too bad the US Army didn't have something like this already going into OEF in A'stan.

All of which could help open the way for a long range intermediate powered GPC to replace both 5.56mm and 7.62mm NATO in infantry (and other combat arms units as seen fit).

It is also possible to rechamber the M24 sniper rifle for .338 Norma Magnum.  An M24A3 varient already exists for .338 Lapua Magnum.  Below is a good side by side pic of both .338 LM and .338 NM:


  • Edited 16/05/2012 00:21 ET by H_Minus

From: carniflex


So the GD MMG is a .338 MG (and yes, I guessed wrong with a CTA gun).

Hopefully they don't use the same advertising team as the FN 15.5mm  :-)

And the round is designed by an American! (No pinky Euro metric calibers)

The .338 Norma Magnum was originally developed by the American sport shooter Jimmie Sloan as a long-range sport shooting wildcat cartridge


From: autogun


The .338 Norma Magnum was originally developed by the American sport shooter Jimmie Sloan as a long-range sport shooting wildcat cartridge.

Jimmie's at NDIA with the gun. I spent some time talking to him yesterday - a really nice guy. The loaded round weighs 702 grains, so although It's almost twice the weight of 7.62mm, you can get 5 rounds for the weight of two .50 BMG.



From: H_Minus


“The LWMMG is an affordable weapon that closes a current operational gap, providing .50 caliber-like firepower in range and effect at the same weight and size of currently fielded 7.62mm machine guns,” said Steve Elgin, vice president and general manager of armament systems for General Dynamics Armament and Technical Products. “Weighing in at 24 pounds and featuring a fully collapsible stock, the LWMMG offers superior mobility and portability in both mounted and dismounted operations.”

I've been talking about the need for a long range .338 MMG for dismounted infantry for years, I'm glad that someone is trying to fill this capability gap.  My hat's off to GD on this one.

"The LWMMG has a firing rate of 500 rounds per minute, a maximum range of 5,642 meters, and is equipped with quick-change barrel technology. In addition to use by dismounted infantry and on ground vehicles, the weapon can be used as the armament system aboard helicopters and littoral craft, providing greater range and effectiveness for those platforms."

All good things IMO.  It should be much more effective on a helicopter than a 7.62mm GPMG. 


From: gearmrk


Excellent news. This should be a very flexible and capable weapon.

I agree with H- that this could assist in adoption of an intermediate round.

Actually, the .338 Lapua has its roots in an experimental sniper rifle cartridge developed for the US Navy SEALs during the 1980s.  That cartridge appears to be based on an even earlier wildcat, the .338-378 KT, inspired by none other than Elmer Keith. 

I wrote up the connections several years ago on another forum.




From: H_Minus


"It looks like it is based on the FN MAG / M240 machine gun with a new fire control system, AR-14 pistol grip, M4-style stock and quad picatinny rails."

I wonder what an AR-14 looks like?

The trigger group with pistol grip looks to me like the one from an M60E4/Mk43:



  • Edited 16/05/2012 10:41 ET by H_Minus

From: RRBud


I like this cartridge concept.

Based on a high-pressure modification of the .416 Rigby case, shortened from the LM, it should indeed point in the direction we've been beating on for the past few years here on Tony's forum.

Of particular interest for me is the realization that the longer, heavier, lower-drag bullets allow this .338 to achieve better terminal effect than its LM predecessor. As you said, it should be a far more effective helicopter-borne MG than anything in 7.62, though a Gatling variant might best be utilized aboard littoral craft in place of traditional .50 BMG.

.50 BMG still has a very significant area of application, but it's being eroded by developments such as this .338 NM.

(edited for typos...)

  • Edited 16/05/2012 12:30 ET by RRBud