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Weapons: Ma Deuce Replacement Stumbles
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July 31, 2007: Two years ago, field testing of the XM-312, the replacement for the eighty year old, .50 caliber (12.7mm) M-2 ("Ma Deuce") machine-gun, began, in the United States and overseas. Then, nothing. That's because the test results were not encouraging, the biggest shortcoming being the low rate of fire (about 260 rounds per minute). This is about half the rate of the M2, and was believed adequate for the 25mm smart shells the XM312 was originally designed for (as the XM307). But for 12.7mm bullets, it didn't impress the troops. There were some reliability problems, which could be fixed. The rate-of-fire issue, however, has proved to be more difficult. Meanwhile, a new upgrade for the M2 has been fielded, and Ma Deuce still rules the battlefield. The new M2E2 has a quick change barrel, flash hider and lot of small improvements. It is much in demand.


Originally, the M2 replacement was going to be the M-307, which was designed so it could fire either the computer controlled 25mm "smart shell" of the XM-25, or (by changing the barrel and receiver), .50 caliber ammo. But it was felt that a straight replacement for the M-2 was needed quickly. The original plan was for the troops to begin getting the XM312 in 2008, or sooner.


The M-2, nicknamed "Ma Deuce" by the troops, has been around so long because it was very good at what it did. Accurate, reliable, rugged and easy to use, many of the M-2s currently in use are decades old, and finally wearing out. The army doesn't want to build new ones, and wasn't sure it could do without the venerable, and very useful, Ma Deuce. So it ended up going ahead with the plan to build a new .50 caliber machine-gun (the XM312). Actually, the new Ma Deuce is basically the XM307, but without the ability to fire 25mm rounds. The XM312 weighs 36 pounds (compared to 50 for the M-2), even with the addition of the electronic fire control stuff from the XM307.


The fire control system, especially the range finder, makes the XM312 much more accurate with first shot hits, than the M-2. American troops have been testing the XM312 in the United States and Germany, and have also reacted favorably to the lighter weight of the XM-312. The lighter XM312 will be easier for infantry to manhandle into position (along with its tripod mount.) But the lower rate-of-fire on the XM-312 was particularly disappointing to the many troops who had used the M2 in combat recently.


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Ed Grimley       7/31/2007 12:06:15 PM
Just typing off the top of my head, but doesnt the basic M2 have a rather low rate of fire to begin with?
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Wicked Chinchilla       7/31/2007 12:45:15 PM
Yes, but it is about twice that of the machine gun listed in the article (about 500-600 Rounds Per Minute).  I was under the impression however that our doctrine was to use it in relatively short bursts as the recoil is significant.  So even though RPM is effectively halved, I would wonder if it would honestly make that much of a difference...anyone more knowledgeable than I care to comment?
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justbill       7/31/2007 12:50:33 PM
Gee, it worked so well on Future Weapons...
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DragonReborn       7/31/2007 1:26:43 PM
The XM-312 is easily converted into the XM-307 so in less than two minutes you can convert it into a grenade launcher with smart shells, two weapons in one.
Looks like it will also be use in the replacement to CROWS
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Something Meatier       7/31/2007 2:05:17 PM
The Ma Deuce isn't exactly a speed demon to begin with.  There's no way I'd want a replacement with half the rate of fire.  Also, in my experience, accuracy was NOT one of its problems!
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sjdoc    What is the *reason* why...?   7/31/2007 2:39:40 PM
...the cyclic rate of fire (RoF) of the XM312 - for euphony, let's call it "the 31-Deuce" - should be so exceptionally low?  What design elements limit the weapon's RoF capability, and can they be addressed to achieve a satisfactory RoF?
By the way, the reason why RoF is so very important to the operation of a crew-served automatic weapon - even if it's only supposed to be fired in short bursts - is that when one does acquire a target and open fire upon it, one really really wants to put a whole buncha rounds on that target as quickly as possible. 
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doggtag       7/31/2007 3:18:09 PM
One of the biggest problems with the M2 has always been maintaining proper headspace.
And the older and more worn the guns become, the less tolerant they are if the headspacing isn't kept precise (shim city).
Another issue that's been experienced countless times throughout the M2's history  (I've seen it twice in 15 years) is runaway guns when they get hot, the best means of stopping them being the crew breaking the belt.
This is where training doctrine has to be written to correct inherent flaws in a weapon design: we'll teach the crews how to stop runaways, rather than engineer the gun to be more safe so as to avoid them altogether.
(but then again, that's partly to blame on crews who don't more carefully manage their bursts.)
That's the reason I favor the Bushmaster Chain Gun in 12.7mm.
It benefits from the safety inherent in all Chain Guns: full control over the feed mechanism and rounds at all times, albeit thru electrically powered operation (not ideal for a man-portable, crew-served tripod weapon).
But that's another plus of the XM307/312's lower rate of fire: the gun's internal dynamics are far less likely to cause runaways if the gun heats up as compared to an M2.
The other thing I see with slower rate of fire of the new gun is, it has an integral scope with some limited magnification ability, whereas unless equipped with aftermarket sights, the M2 only has adjustable irons.
So if I can zoom in a little better, and my gun has a lower recoil and is more stable, does the fact I fire less rounds but better aimed make for a better weapon than one with a higher rate of fire which also lends to its higher peak recoil and more bouncing around unless in a solidly anchored mounting, which in turn causes greater dispersal downrange... the point being, this all sounds like the "spray and pray" crowd who loves automatic fire (regardless of how accurate or not their shots are downrange) are suddenly crying fowl because now they're being encouraged to actually take better aim first (even if it wastes less shells doing so).
Anyone have the accuracy of the new gun to compare it to the M2, as far as MOA dispersal at given ranges?
If I can place more rounds more precisely by firing even half as fast, doesn't that technically overcome all the rounds of the faster-firing gun that impact away from where I was aiming the gun to begin with?
One thing that can be noted about both the Bushmaster 50 and the XM312: both of them have shorter barrels than the Browning gun, which equates to less maximum velocity, and in the end a lower range.
But knowing Chain Guns (Bradley mechanic, among other things), there wouldn't be a lot of difficulty in modifying the basic gun components to handle a longer barrel and greater chamber pressures to get higher velocities and greater ranges.
Looking at the XM312, with its long stroke recoil mechanism being part of the reason it's more stable (see the glass of water trick in the Future Weapons video), I seriously doubt this new gun could handle much of a barrel length increase, and the resulting higher chamber pressure, projectile velocity, and stronger recoil impulse.
Seeing as the majority of M2s in use today are being fired from vehicles anyway, or at checkpoints near enough to power supplies running radios and observation equipment, I personally would just as soon opt for the Bushmaster gun, but with a better barrel.
(and anyone here whose ever swapped out a Bradley's 25mm barrel (M242 series gun) knows that it barely even takes a couple minutes to pull the release handle inside the turret above the breech & feeder assemblies, twist the barrel, pull it out, put in another one, twist it, and be sure the handle locks. It ain't rocket science to change a 25mm barrel, so a 50-cal model should be a cake walk.)
And now that ATK have themselves developed a Chain Gun variant that can fire these new smart fuzed 25mm rounds, I'd wager that they'll shortly demonstrate that with minimal in-the-field modification, their new LW25 can convert to 12.7mm just like the XM307/312, even if it ends upa bit longer to do so.
 It all depends on how adaptable the core components are. Supposedly, the Bushmaster III can convert quickly from 35mm to the 50 SuperShot, just as the Mk44 can supposedly quickly modify from 30x173 to fire the Super 40 telescopic ammo.
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Shieldwolf       7/31/2007 8:00:37 PM
A question on the accuracy of the M2 as a sniper system? 
In 1967, Hathcock set the record for the 20th century's longest combat kill with a Browning M2 .50 BMG machine gun mounting a telescopic sight. The distance was 2,286 meters or 1.42 miles. Hathcock was one of several individuals to utilize the Browning M2 machine gun in the sniping role. This success led to the adoption of the .50 BMG cartridge as a viable anti-personnel and anti-equipment sniper round.  This shot has been verified multiple times, it is reality, not a myth or tall tale.

Second, the idea that the M2 replacement would have a firing rate of less than half of the M2 is ridiculous : the M2 is designed for more that shooting at humans, and you want the quick multiple hits against vehicles - especially light armored ones.  That slow rate of fire is ONLY acceptable with the 25mm round since it has HE and shrapnel features : a 25mm HEDP exploding next to one is most unpleasant and will do enough damage to require only one round impacted.

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YelliChink       8/1/2007 1:34:20 AM
XM312 weighs only 19kg without mount. M2HB weighs 38kg. The answer is simple to me: JUST GET A DOUBLE MOUNT!
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Alex N       8/1/2007 5:48:15 AM
I was a 0331 (machingunner) in the USMC from1997-2001 with the 7th Marines Reg. stationed out of 29 Palms Ca. I was stationed with Fox Co. so my primary weapon was the M240G 7.62mm, but I had extensive training and trigger time on the M2HB 12.7mm (.50 cal.) and the MK19Mod 3 40mm automatic grenade launcher.
    I have never seen a runaway gun on the M2HB, I have seen a few on the 240, including one where the pin that holds the trigger group to the receiver vibrated out and and the gunner handed me the trigger group while he continued to fire out remaining rounds. A few points on runaway guns. First the M2 ammo is in fifty round boxes the M2 rate of fire is 450-550 RPM ( All the numbers I give in my reply are from my old Division School 0331 course book Dated 21 Nov 1996 sorry no FMF Ref Nam .) 50 rounds are/is not going to last long. The 12.7 mm ammo is on nondisentigrating links unlike the 7.62 and linked 5.56 you can't simply twist the belt and break it off. We were taught that with a runaway gun if friendlies are not in danger you fire out the remaining rounds than reload or take the gun off line. Even with the 7.62 and 5.56 if you twist the belt you run a high risk of damaging the feed pawl assy.
   Some comments on weights of the M2HB. Receiver Group 62 lbs, Barrel Group 24 lbs. M3 Tripod with Traversing and Elevating Mech. 44 lbs. Total weight 128 lbs and 65 inches overall. All 3 groups can be carried separately I did at least one 20 mile hike and many smaller hikes carrying the M2 you have to trade off the different groups among the team so you don't get fatigued. Anyone out their remember MCAGCC in August.I am only 5'8" and back then 175 lbs and had no problems humping Ma Deuce. The old MachineGunner adage "Fun to shoot a bitch to carry." When I was in, the MachinGunners in my Battalion took pride in out humping everyone else.
   The U.S. Army needs to pony up and realize that their is no replacement for the M2HB utterly reliable and legendary. Grandpa had one in WW2, Dad in Nam and still going strong. FN Herstal is still making new M2HB's it is their Quick Change Barrel the article refers to, they also make a excellent High Explosive Armor Piercing Incendiary round. I have a picture in a book The Browning M2 Heavy Machine Gun by Terry J. Gander copyright 1999 on page 22 are 2 pictures taken during the 80's of the RAMO M2 production line, that tooling is not destroyed.U.S. Army wants a new and improved version it is not economically feasible to restart production on a weapon that is still performing admirably. It is cheaper to start over from scratch, how many millions of dollars have been spent to replace the M2HB and yet the replacement can't meet the standards.If it ain't broke don't fix it. Stop referring to the .50 in the past tense, and long live John M. Browning's greatest design.       
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