In an effort to lessen the weight infantry have to carry in Afghanistan, several hundred commando style Mk 48 7.62mm machine-guns are being sent. These are nine pounds lighter that then standard, 27.6 pound, M240 machine-guns they will replace. SOCOM (Special Operations Command) has been using the Mk 48 for eight years now. SOCOM troops need the light weight for commando operations. But that light weight comes at the expense of durability. The lighter components don't last as long. For example, the M240 bolt and receiver are both good for 100,000 rounds fired. But on the Mk 48, the bolt has to be replaced after 15,000 rounds and the receiver after 50,000. This was not a problem with the commandos, who made sure they had plenty of spares available, and kept track of the (approximate) number of rounds fired. Not so hard to do, you just have to pay attention.
The nine pound savings with the Mk 48 makes all the difference when it comes to carrying a 7.62mm machine-gun with you. The M240 is so heavy, that troops rarely take them away from the vehicles they are usually mounted on. But the Mk 48 is less heavy enough to justify hauling with you up those Afghan hills.
The Mk 48 began as a scaled up 17 pound M249 (the standard 5.56mm) light machine-gun. The Mk 48 only weighs a pound more, and troops always take their M249s with them. Of course, the 7.62mm ammo is heavier (each 100 rounds of 7.62mm weighs two pounds more than 100 rounds of 5.56mm). But the Mk 48 is usually fired in short, six round, bursts. So a few hundred rounds will last a while.
The introduction of the Mk 48 is just one of many new, lightweight, items being introduced in Afghanistan. New, and lighter boots, tools and body armor will lighten the infantryman's load by an average 13 pounds (5.9 kg). This is a big deal for grunts who spend hours marching and running around carrying 60-100 pounds of gear.
It took years of complaints from the infantry, including everyone from officers to NCOs to the newest grunt to arrive, before the U.S. Army was moved to try something drastic about the weight situation. This effort has seen the troops being equipped with the lightest substitutes the army could find for body armor, packs, boots and other gear, while simply leaving some stuff out entirely. This resulted in twenty or more pounds, depending on the mission, being removed from the soldiers combat load.
The biggest, and heaviest, problem is body armor. Although the new armor offers better protection, it is heavier and bulkier, thus inducing fatigue and hindering mobility. This often led to battlefield situations where a less tired, and more agile, infantryman could have avoided injury. Military and political leaders usually do not appreciate this angle. But the troops do, as it is a matter of life and death for them.
Senior commanders are under a lot of pressure to keep friendly casualties down, so they tend to insist that the troops wear all their armor all the time. Despite this, some subordinate commanders look the other way when troops shed some of their armor temporarily to get some needed speed. The new protective vests have a quick release feature, that makes it easier to get the vest off, and back on again.
Many soldiers and marines point out that the SOCOM operators (Special Forces and SEALs) will sometimes go into action without their protective vests. Again, that is done because completion of the mission is more important than covering your ass when a reporter goes after you for "unnecessary casualties." Many of the troops are willing to take the risk, because they believe, for example, that taking down a sniper when you have the chance, is worth it. If you don't catch the guy, he will be back in action the next day, killing Americans.
Currently, the lightest load carried, the "fighting load" for situations where the troops were sneaking up on the enemy and might be involved in hand-to-hand combat, is 63 pounds. The "approach march load," for when infantry were moving up to a position where they would shed some weight to achieve their "fighting load", is 101 pounds. The heaviest load, 132 pounds, was the emergency approach march load, where troops had to move through terrain too difficult for vehicles. As in the past, the troops often ignored the rules and regulations and dumped gear so they could move, or keep moving.
In Afghanistan, the problem is made worse by the high altitudes (up to 5,000 meters) the troops often operate at. The researchers found that in Afghanistan, even though the infantry were in excellent physical shape, troops would sweat nearly 20 ounces of fluid an hour while marching at high altitudes in bright sunlight in moderate temperatures. That meant more weight, in water, had to be found to keep these guys going.
A lot of the weight carried is essential stuff. Weapons, for example. The Army saved two pounds in the 1960s when they switched from the M-14 rifle to the M-16. A lot of weight was saved in ammo carried as well, because a hundred M-16 bullets weighed two pounds less than a hundred M-14 ones. Troops usually carry 200-300 rounds of rife ammo with them. Plastic canteens replaced metal ones and lighter sleeping bags showed up, as well as lighter clothing. Lighter food (pouches of MREs instead of cans of C Rations). But heavier stuff was added, like the 17 pound "Interceptor" bullet proof vest and the heavier Kevlar helmet. Special Forces troops often go into action without body armor, and keep the load under 40 pounds. But that's only in those situations where the Special Forces calculate that speed and achieving surprise are worth more than the protection the vests provide. Most troops do not have that option, but they do need less weight on their back to remain competitive with the enemy they fight in rural Afghanistan.