Replacement for Ma Deuce

US Army’s New Heavy Machine Gun

Strategy Page has a post up about the XM307, the replacement for the M2 .50 cal machine gun that’s been in service since shortly after WW1. The weapon was originally designed to fire 25mm “smart shell” grenades like the XM25, but the Army decided it was finally time to retire the good old “Ma Deuce” M2 and, with a barrell change and a receiver swap, the XM307 will be transformed into a standard .50 caliber machine gun.

The XM307 is 14 pounds lighter than the M2, and some of its smart shell electronics, like a laser range finder, will also be usable with the .50 cal configuration. The big question probably is the reliability and durability of the new weapon. For 80 years the M2 has proven itself, and I’m sure that not everyone is excited about the “upgrade”. We’ll see.


  1. With all the weapons, vehicles, and individual gear which actually NEED IMPROVEMENT, and with some needed improvements getting cut for budgetary reasons, I have to wonder WHY we’re developing a replacement for one of the most reliable firearms ever invented. The replacement, while lighter, is still too heavy for one person to carry very far, so no weight problem has been solved. Developing a good weapon to fire the XM25 is fine [given the OICW grew bigger than a Super Soaker and a lot heavier, making it impractical, leading to a split-out to the XM8 (mini-soaker) and a future bigger airburst water bomber], but I’d leave it at that. One good outcome of another case of misdirected military-industrial complex thinking is that a lot of obsolete Ma Deuces will be put on the military surplus market, which is great for those with Class 3 licenses. What’s next? A replacement for the B52? If a weapon gets the job done, and is reliable, why replace it with a weapon which adds no advantages? Just upgrade it. If a new weapon offers a quantum leap forward, by all means, go for it. Airburst charges which can be exploded over the heads of a cluster of enemy will be the next quantum leap in anti-personnel weapons, I’d say. A weapon which optimizes the firing of such rounds, in the hands of one man per fire team or squad, will be well worth the development and deployment cost. Let’s not complicate it by making the barrel interchangeable for .50 BMG. Simple things tend to be more reliable and easier to support. Sometimes the Marines can be jarheads, but I’d say they made a smart decision in ordering the M16A4. The only suggestion I would have made is to go with the 6.5mm Grendel or at least the 6.8mm SPC. But, of course, they didn’t ask me. ;-) Keep up the good work searching for weapons developments, Murdoc. ACE (entitled to Murdoc’s opinion, as well as his own)

  2. Why replace the M2? 1) They are going to need to buy some new ones anyway. Why not make them lighter and add new capability? I agree, though, that the 307 better have the reliability of the M2. 2) There were some complaints out of Iraq that the heavy machine guns could use a better sighting system. Soldiers mainly use tracers to aim, so they don’t have good first shot on target ability. Laser range finder was specifically requested by the troops. (IIRC, that was the only complaint about this weapon, since it has super reliability and provides great firepower. Well, there were some complaints about the mounting systems on vehicles — HUMVEE for instance — but that’s a different issue.)

  3. AH, the venerable M-2, 50 cal. finally being layed to rest after 80 years. I hope the replacement doesn’t need to have its ‘head space’ adjusted after every 100 rounds or so!

  4. A few thoughts in response to what has been posted here. The M2 is a good weapon, but is too heavy and is not all that reliable – suffering a jam about every 2,000 rounds if memory serves. This is in contrast to the M240 which suffers a jam once every 40,000 rounds. For the same weight they could go with twin M240’s. It would be better for closer, softer targets and worse for long-range or harder targets. The MG on an armored vehicle should always be capable of taking down an infantry TOW weapon outside of the TOW’s max range. I think the case for the OCSW rests far too heavily on the air-bursting ammo’s effectiveness. If someone were shooting at me with air-bursting ammo I would simply cover my trench or firing position. I think a much more effective solution could be had much more cheaply, a small mortar or even 40mm grenade that can find a GPS coordinate or find a laser point. There currently exists a GPS round for the 120mm mortar so the technology exists. Why is this a better solution? Because it provides both direct and indirect fire support. If one reads the after-action reports from Operation Anaconda it is clear that except for the .50 cal, no direct fire weapon had the range to engage the enemy after initial contact. If able to put a 60,81 or 120mm mortar on any target one can laze, or get a GPS coordinate for, ANY mortar fire becomes incredibly effective and can be used from the back sides of mountains as is common in mountainous terrain such as Korea or Afghanistan. Reverse-slope mortar tactics dominated the fighting in the Pacific campaigns in WW-II, Korea, and now in Afghanistan. Btw, the CAS in Anaconda was consistently unable to effectively engage small groups of Taliban soldiers, and the aircraft refused to fly in many cases for fear of getting hit by mortar fire

  5. I agree with the 6.5 Grendel as a replacement for 5.56 NATO. …but not the 6.8 SPC. Ballistics Comparison: 6.8 SPC / 6.5 Grendel Sierra 115 gr / 123 Scenar Lapua .340 BC / .542 BC 2422 / 2427 fps at 100m 1498 / 1609 ftlb at 100m +6.06 / +5.76 in drop at 100m 1.20 / .90 in drift at 100m (10mph) 1916 / 2102 300m Velocity 938 / 1206 300m Energy 0 / 0 300m Drop 12.05 / 7.49 300m Drift 500meters: 1488 / 1803 Velocity 565 / 888 Energy -52.41 / -43.73 Drop 37.8 / 22.41 Drift

  6. A 6.5mm round that was designed like the SS109 5.56mm round would probably be very effective in terminal ballistics. The longer 6.5mm round with steel penetrator forward core and heavier lead rear core would become very unstable in soft tissue. Tumble would be likely to occur very quickly. The longer 6.5mm bullet would be more off balance than the 5.56mm round. The longer 6.5mm bullet would also suffer more stress as it tumbled and be more likely to break up at lower velocities than the 5.56mm round. The greater instability in soft tissue combined with the additional stress on a longer bullet should allow the 6.5mm round to fracture at distances beyond the 200m of the 5.56 fired from a 20′ barrel. A final step would be to place a cannilure on the 6.5mm round at the point where the differing cores meet. This would ensure breakup at the lowest possible velocity.

  7. UPDATE: Why are you stating the energy of a bullet at 1000m when you can’t even see that far? Short-range penetration, recoil, and wwight are the most important factors.

  8. SniperDude: Those handgun rounds will NOT penetrate body armor, not even at point-blank range. Our SOF guys reported that even the low-rent Taliban in Afghanistan had old soviet body armor that 5.56 didn’t penetrate at range. Going forward it must be assumed that all enemy combatants will have body armor. Second, almost all of our rifles are now scoped, and any mediocre shot can hit a target at 1,000 yards with the proper gun, scope and bullet. It doesn’t make the evening news because newsies hate to hike, but in most of the terrain we are patrolling a thousand yards is the minimum useful range. Look up the after-action reports for operation Anaconda, or Iraqi Freedom, or understand why the German MK-42 MG used the 7.92×57 after early experience in the desert made it obvious it was better to have range they didn’t need than need range they didn’t have. With body armor it is the need to reach out and penetrate body armor at 1,000 yards that must drive caliber decisions. The Operation Anaconda after-action report in particular said clearly that only the .50BMGs the Canadians brought (confirmed kill at 2435 yards!) and 120mm mortars were of any use after initial contact. The after-action report for OIF pointed to the Barrett .50BMC as the most effective weapon available to light fighters with devestating psychological affects on the enemy. As a result of these shortcommings our SOF guys are now using .338 Lapua Magnum and .408 CheyTac and .50BMG for long-range engagements. For the standard infantry rifle the 6.5 Grendel is just better than the rest, and can be improved still further by using bullets with driving bands, higher twist barrels and very long/high BC bullets. The 7.62 was too big when we fielded it over the objections of the British, who had it right all along, it looses energy too fast, and if you give it a high BC bullet, it is far too heavy of a round for a general purpose rifle, kicks too much, and will not fit in current actions as the bullet would be too long. Since the average guy is now humping around 9-14lbs of body armor in the blistering heat of the desert, weight is a very important consideration. We aren’t fighting in Europe or Vietnam any more, it’s time our weapons reflected this, in fact, it’s way past time. solidpoint Google rules!