scout sniper student, fires a .50 caliber M107 special application scoped rifle during scout sniper training, July 2. The Scout Sniper Instructor School is part of the Weapon’s Training Battalion aboard Marine Corps Base Quantico. - scout sniper student, fires a .50 caliber M107 special application scoped rifle during scout sniper training, July 2. The Scout Sniper Instructor School is part of the Weapon’s Training Battalion aboard Marine Corps Base Quantico.