The HK416, which was developed for U.S. special forces, bears an outward resemblance to the M4. But inside, it uses a short-stroke gas system that proponents say constitutes a vast improvement over the M4's design. The rifle has been used by the Army's Delta Force since 2004 after tests determined that the HK14 piston operating system cut down on the frequency of malfunctions while extending the life of its parts. If he had a vote, Major Chaz W. Bowser, a former weapons developer for the U.S. Army's special operations branch, made clear what his preference would be: "I could go to Iraq or Afghanistan or anywhere with whatever weapons I wanted to carry. As soon as the H&K 416 was available, it got stuffed into my kit bag and, through test after test, it became my primary carry weapon as a long gun. I had already gotten the data from folks carrying it before me and had determined that it would be foolish to risk my life with a lesser system," he wrote in a letter to Army Times.