The US Army issued a contract to build a new heavy machine-gun, the M307. It can fire 25mm "smart shells" or, with a barrel change, the older .50 caliver (12.7mm) bullets. Earlier, it planned to build a new .50 caliber machine-gun, the M312. Now it’s official, the U.S. Army is building a replacement for the 1920s era M-2 .50 caliber (12.7mm) heavy machine-gun. The new weapon, the M-307, has been designed so it can fire either the computer controlled 25mm "smart shell" or (by changing the barrel and receiver), .50 caliber ammo. The troops will begin receiving the new...