Staff Sgt. Elizabeth Gregson, a 28th Security Forces Squadron combat arms instructor, inspects an M4 bolt carrier at Ellsworth Air Force Base, S.D., Sept. 10, 2018. Members assigned to the 28th Security Forces Squadron combat arms training and maintenance flight conducted their biannual inspection of all weapons on base to ensure they are ready for use in a deployed environment and for training purposes. (U.S. Air Force photo by Airman 1st Class Thomas Karol)