Shell casings fly as Air Force Staff Sgt. Christopher Oshana fires an M-9 handgun. Shell casings fly as Air Force Staff Sgt. Christopher Oshana fires an M-9 handgun during proficiency training at MacDill Air Force Base, Fla., on March 27, 2006. Oshana is an Air Force combat arms training and maintenance instructor with the 6th Security Forces Squadron at MacDill. The instructors are required to fire 500 rounds a year on every small arms weapon they teach in order to stay proficient as instructors. SHARE: Download: Full Size (0.02 MB) Credit: VIRIN: 710415-N-SGM15-250.jpg Photo Gallery