Originally the Marines (just from my experience) used them as their designated marksmen weapons. I went up to designated marksman school in Chesapeake, Virginia, we fired with the modified M14's while there. Then later on in my career we went to Guam where we got to test and evaluate the newer Squad Designated Marksman rifles that the Warfighting lab was contemplating buying. We ended up picking a heavy barreled colt and the trijicon optic. After going to the school we never really saw much of the M14 anymore.