USMC MACHINEGUN TACTICS; 

@The Marines are famous for their "talking guns" tactic, in which two machineguns work in tandem. Each gun fires a short burst, then waits to hear the other gun fire its short burst before firing another. This ensures that the bursts are the proper six-eight seconds apart. Talking guns doesn't really help when the two machineguns are firing on different targets, although it does help each gun maintain its timing. It would be better to train each gun crew to count its own intervals as it is difficult in combat to hear clearly what the other gun crew is doing. 

@ There is also a tendency of one gun to increase its rate of fire when the second is reloading. This doesn't accomplish much if the two guns are not firing on exactly the same target. Doctrine calls for the gunner's left hand to remain on the elevating wheel of the traversing & elevation mechanism. This allows the gunner to adjust the fall of his rounds as needed or as directed by the team leader. Without intense training, however, the gunner has a tendency to move his hand back to the gun after each adjustment. This makes the weapon less stable and harder to adjust quickly. The training of gun teams (on a static firing range) tends to get them used to thinking that they are fighting alone rather than as a part of a platoon. 

@ Troops must be trained to maintain situational awareness. During training maneuvers, a sergeant or officer should ask the team periodically what else is going on around them to encourage them to keep the broader picture. When two machineguns are working together (something the Marine Corps fanatically insists upon), the junior gun crew should be deployed farther forward than the senior crew. This will allow the senior team leader to keep an eye on the other gun and coordinate barrel changes and reloading. One good trick is for one gun to start with a 100-round belt and the other with 200 rounds. After firing the initial belt, each gun uses 200-round belts. This helps stagger the reloading cycles. 

@ The doctrinal rate of fire is a burst of 6-8 rounds followed by a pause of 6-8 seconds. As a practical matter, if friendly troops are not exposed while advancing on the target, a pause of 10-12 seconds will be adequate to keep the enemy pinned down. 

@ Mark-19 grenade launcher crews need to remember that they are one of the few weapons capable of engaging enemy forces behind cover or in defilade. If the Mark-19 rounds are striking a target which can be seen and killed by other weapons, something is wrong. Mark-19 ammunition is bulky and should not be used when other weapons can do the same job. The 40mm grenades will penetrate two inches of steel armor while .50-cal machinegun rounds will penetrate only one inch, so if the target is lightly armored, the Mark-19 may be the best weapon for the job. 

@ It could be hoped that at least 60% of US military operations are offensive in nature, but 95% of machinegun training is in defensive tactics and engagements. Gun crews should be trained in how to select and occupy a firing position while remaining under cover. One training technique is to tape a laser pointer to a cleaning rod. Insert this into the barrel of the weapon when dry firing inside a dimly-lit armory, and the team leader can track the abilities of the gunner to aim and adjust his weapon. 

@ Gun crews should carry empty sandbags to help them set up interim firing positions during an advance. If they have access to a vehicle, they should have filled bags on it to get the gun into action faster. 

@ Medium machineguns (M60 or M240) are not the same as heavy machineguns or Mark-19 grenade launchers. Gunners moved from one system to the other require formal retraining in order to establish the mindset. Medium guns use high rates of fire to suppress positions or break up attacks. Heavy machineguns are best for attacking vehicles or bunkers. Mark-19s are best when used to engage light armor, heavy bunkers, or troops in defilade.--Stephen V Cole