U.S. Air Force Senior Airman Nicholas Niles tells Airmen to aim their M16A2 rifles at a target in a classroom during a combat arms training and maintenance course at Barksdale Air Force Base, La., Aug. 18, 2011. The Airmen later qualified with the M16A2 rifle while wearing a helmet and body armor. Airmen in the course also donned gas masks to help them get used to using the weapon in a contaminated environment.