The XM8 is a rifle made by Heckler & Koch. It is an automatic rifle that uses the 5.56 mm NATO caliber ammunition. The XM8 holds 30 rounds of ammunition. The US Army was interested in the XM8 because it is a very light weapon. It weighs only . The US Army tested ten weapons in a 60,000 round dust test and the XM8 was the best. This showed that the XM8 is much more reliable than the M4.