CALIBER QUALIFIED U.S. Air Force Senior Airman Elizabeth Gonzalez looks over the flightline on Sather Air Base, Iraq, with a .50 caliber machine gun, March 26, 2009. Gonzalez, one of a few security forces members qualified on the .50 caliber machine gun, is assigned to the 447th Expeditionary Security Forces Squadron. SHARE: Download: Full Size (0.07 MB) Credit: VIRIN: 376300-C-RCQ90-775.jpg Photo Gallery