The Marine Corps ' newest sniper rifle is ready for prime time. Marine Corps Systems Command announced Tuesday that it has reached full operational capability for the service's new Mark 22 Advanced Sniper Rifle, which means that all infantry and reconnaissance units have fielded and completed new equipment training on the system. The rifle is based on the Barrett Firearms' Multi-role Adaptive Design bolt-action sniper rifle and is capable of chambering 7.62x51 mm NATO, .300 Norma Magnum, and .