BACK BLAST U.S. Marines create a back blast as they conduct a live-fire exercise with the AT-4 rocket launcher on Camp Atterbury, Ind., Sept. 28, 2009. The Marines are assigned to Force Reconnaissance, 24th Marine Expeditionary Unit. SHARE: Download: Full Size (0.07 MB) Credit: VIRIN: 449760-U-NHH45-739.jpg Photo Gallery