Many units are supplemented with a variety of specialized weapons, including the M249 SAW (Squad Automatic Weapon), to provide suppressive fire at the fire-team level. Indirect fire is provided by the M203 grenade launcher. The M1014 Joint Service Combat Shotgun or the Mossberg 590 Shotgun are used for door breaching and close-quarters combat. The M14EBR is used by designated marksmen. Snipers use the M107 Long Range Sniper Rifle, the M2010 Enhanced Sniper Rifle, and the M110 Semi-Automatic Sniper Rifle.

Answer this question, if possible (if impossible, reply "unanswerable"): What gun do designated marksmen use the least?
unanswerable