THE HEAVY MACHINEGUN CREWMAN MCI 0368A1. Purpose. MCI course 0368A, The Heavy Machinegun Crewman, provides distance training to all Marines.2. Scope. MCI course 0368A, The Heavy Machinegun Crewman, is designed to provide fundamental and some advanced principles in employing the M2 HB .50-caliber and MK19 40mm machineguns. This course emphasizes identification of major components, assembly, system checkout procedures, loading, and target engagement. This course will also provide instruction on immediate action procedures and care and maintenance.