Staff Sgt. Micheal Mitchell, left, fires the MK19 40mm grenade machine gun Monday from the top of a Humvee at Ruth Range. At right is his spotter, Pfc. David Behrend. The two were among 10 Soldiers from B Company, 2nd Battalion, 29th Infantry Regiment, who took part in the Maneuver Battle Lab's weeklong experiment on a modified rear sight for the weapon, which also is pictured. Officials said the new design could lower manufacturing and maintenance costs.