[Cannoneer No. 4]

This soldier is mounting the Remote Weapons Station for the Mk 19 automatic grenade launcher on his Stryker. Turreted vehicles would be too high to drive up the ramp into the C-130. The RWS is not stabilized and the vehicle must come to a stop to fire the weapon accurately. The high-tech RWS is less capable of shooting on the move than a free gun on a pintle mount.

[historian1944]

That caption isn't quite right, it should read that the soldier is mounting a MK19 onto an RWS. The RWS is permanent. For air transport it is folded down.