A safely cleared M4 rifle rests silently while Airmen check and evaluate the accuracy of their fire during a 28th Security Forces Squadron Combat Arms Training and Maintenance rifle course on Ellsworth Air Force Base, S.D., Jan. 9, 2011. Airmen gain proficiency with the weapons by firing rounds at targets in different positions. (U.S. Air Force photo by Airman 1st Class Zachary Hada/Released)