FIRE BASE SAENZ, Helmand province, Afghanistan - Lance Cpl. Christian R. Stark, a field radio operator and a provisional artillery cannon crewman, pulls the lanyard of the M777 A2 Howitzer. The cannon crewmen making up each gun are from various military occupational specialties, each performing duties within their certifications. A field radio operator may be qualified to fire the howitzer, but only a field artillery cannoneer can handle powder charges and ammunition.