September15, 2008:  The U.S. Army has given up on getting a replacement for the nearly century old M2 .50 caliber (12.7mm) machine-gun. At least not anytime soon. Many of the current ones are wearing out, so the army is replacing over 80 percent of its 36,600 M2 machine-guns in the next five years, with new M2s. Efforts to develop a replacements for the M2 have failed so far.

For example, three years ago, field testing of the XM-312, the chief contender to replace the M-2, 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 (the M2 has one jam per 10,000 rounds), which were believed fixable. 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. Didn't happen.

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 didn't want to build new ones, and wasn't sure it could do without the venerable, and very useful, Ma Deuce. So it tried to develop a new .50 caliber machine-gun (the XM312). 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. American troops testing the XM312 also reacted favorably to the lighter weight and fire control electronics. But the lower rate-of-fire on the XM-312 was a deal killer to the many troops who had used the M2 in combat recently.

The 25mm "smart shell" of the M307 is still a promising concept, but what the troops really want is a heavy shell that can fire through walls, vehicles and take out enemy troops with one bullet. The 12.7mm bullet does all that. For long range grenades, the troops still prefer the 40mm Mk19. The army has 23,000 of these, and many are old and worn out. Not as bad as the M2 situation, but the army is buying 4,600 new ones over the next few years.

Both the M2 and Mk19 have a max range of 2,000 meters. The Mk19 rate of fire is about 350 rounds a minute, and is usually fired in short (a few rounds) bursts of these 19 ounce grenades (which kill or incapacitate most people with six meters of the explosion). The Mk19 is more complex and expensive ($22,000 each) than the M2 ($14,000 each) and jams more frequently. But it is reliable enough to remain popular and in demand.

The M2 has become even more popular with the addition of night and thermal sights. With these, you can spot enemy troops, over a thousand meters away, at night, as they try to sneak up on you. You can eliminate the threat before they get within rifle or RPG range.