Later this year, the U.S. Army will equip two brigades with a prototype of the new XM8 5.56mm assault rifle. This will allow for intensive field use of the rifle to work out any deficiencies in the design.
The XM-8 is based on the very successful Heckler-Koch G36 assault rifle. It was this rifle that was modified to serve as the 5.56mm portion of the XM29 OICW weapon (which has a 20mm computer controlled weapon on top). The XM29 proved to be too heavy and bulky during field tests, but users were very impressed with the Heckler-Koch portion of the weapon. Actually, the 20mm computer controlled portion of the weapon was liked as well, but to solve the weight problem, a separate 25mm weapon (the XM25) is being developed. At the time, it was suggested that the 5.56mm portion of the XM29 was a superb weapon and might make an excellent replacement for the four decade old M-16. So the decision was made to develop the Heckler-Koch 5.56mm weapon into a new American assault rifle.
Last Fall, 200 prototype XM8s were ordered and put through tests. The rifles were fired thousands of times, without being cleaned and in dusty and sandy terrain, and the weapons didn't jam. This was no surprise, as Heckler-Koch had developed an innovative mechanism for the G36 that keeps crud from building up and jamming the firing mechanism. While the major appeal of the XM8 is reliability, Heckler-Koch designs are also noted for their flexibility. The XM-8 is a modular weapon, taking three different barrels for different functions. Most XM-8s would look similar to the current M-4, with a shorter barrel than the M-16. There would be a longer barrel for sharpshooters and snipers (longer than the M-16 barrel) and a heavy barrel, of about the same length as the M-16, for the XM-8 when used as a light machine-gun. There would also be a "commando" version with an even shorter barrel and, with the butt stock folded, is only 20 inches long. This would be for use in tight spaces, and for vehicle crews. There has been a big demand for this sort of thing in Iraq, where vehicles get ambushed a lot and people in the vehicles want to get their rifles out and firing as quickly as possible.
For all but the commando version, the barrels can be changed by the unit armorer (with some special tools.) Instead of the different optical systems currently available for the M-4/M-16, the XM-8 would have one system combining a red dot reticule, a backup sight that requires no power, an infrared pointer, an infrared illuminator and a visible pointer. The multipurpose optical system will be popular with the troops, since they will only have to zero one optical system, but be able to use all of them.
There would also be parts available to quickly convert XM-8s to fire AK-47 ammo (some M-16s are already available with that modification.) Special Forces troops often use this type of weapon, when operating in areas with lots of AK-47 ammo. The XM-8 will not have the three round burst fire mode M-16s have had since the 1980s. The mechanism that allowed the three round burst has caused reliability problems, and most officers now agree that well trained troops can handle using full auto fire (and any problems with running out of ammo.) The G36 has other innovations that will probably show up in the XM-8, like the magazine with clear plastic on one side, so that the soldier can just look to see how many rounds he has left.
Equipping entire brigades with XM-8s as a large scale test shows great confidence in the weapon. But this should not be surprising, as the G36 that the XM-8 is based on has been around for years. The German army began using the G36 in 1995, and other European armies (and U.S. troops stationed in Europe) quickly noticed that it was an exceptional weapon. If the XM-8 does replace the M-16, it will probably be built in the United States by Heckler-Koch, and by one or more American firms under license.