On higher difficulties, it is key to detach the turret; being stationary, the enemy will be able to flank you or fire on your position with ease.
During the most difficult encounter on Tsavo Highway, it is advised to detach the turret and pull to the back of the buildings and begin taking down jet pack Brutes, then if the opportunity presents itself lay into the Chieftains with it.
Take advantage of the AIE-486 on Crow's Nest during both the hangar encounter and the Landing Pad Bravo encounter. The turret will work well at chipping away at the jet pack Brutes' shielding, allowing your allies to take them down more quickly.
In both Campaign and Multiplayer, a player model carrying a detached turret moves faster when moving diagonally or sideways.
The Machine Gun Turret is not as powerful as the Warthog's LAAG, so be careful when taking on an undamaged, unengaged Warthog, or else you'll quickly wind up dead. Only fire upon Warthogs that haven't seen you and are concentrating elsewhere.
A way of moving faster with the turret can be done by constantly dropping and picking up the turret. This, while looking like you're dribbling the gun, allows almost normal movement. Be aware of other weapons lying around, as you might pick one of those up instead.
HMGs are easily detached using explosives. A good tactic is to grenade the turret instead of detaching it to reduce the amount of time in a stationary position, although this will also move the detached HMG away from the explosion, which can lead to it being lost or worse, enemies obtaining it.
Detaching the turret in Multiplayer has its advantages and disadvantages. You will move more slowly, making you more vulnerable to small arms fire and grenades. It is tactically wise to only use the turret in defensive situations that will provide good cover. If you have the opportunity to use the turret on offense be sure to have another player backing you up as you lay into the other team.
It is a bad idea to use the turret for long periods of time on sniper matches.
Breaking a turret without using any weaponry is made easy by standing on top of it, crouch-jumping, and letting go of the crouch button before you hit the ground.
Do not underestimate the power of leaving the weapon attached to its mounting. While mounted ammunition is effectively unlimited and thus the weapon can produce a tremendous volume of firepower. This can be effective at tactically suppressing particular fire zones from enemy advance, and forcing snipers to keep in cover. It will draw a great deal of the enemy's attention, forcing them to expend strength trying to counter it.
You turn much slower than normal when carrying a turret, watch your flank and try to be as evasive as possible.
If engaged in a team match, it can be wise to occupy the weapon while mounted if one has a team mate to watch the flank. This team mate can help pick off enemies that the turret cannot reach and to warn the team mate operating the turret when the enemy is moving in on the flank so that both can relocate or deal with the threat.
On Standoff, the turret can be an excellent defensive tool, since there are no snipers on this map you can mow down enemies with ease. Your biggest threat is the Spartan Laser, but if your team controls it, the only other thing you need to watch out for is getting flanked by a fast Warthog.