In the campaign, the M739 SAW first appears in Requiem. It appears again in Shutdown and Midnight, the latter mission giving the player the SAW as a starting weapon after the F-41 Broadsword sequence.
As with the MA5D assault rifle, the M739 SAW is most effective at close range with its trigger held until the target has been eliminated, and fired in short, concise bursts at moderate ranges. The M739, however, is much more accurate than the MA5D with its slower bloom increase, allowing the user to fire much longer bursts and engage targets at much longer ranges.
The SAW has a much faster kill time then normal starter weapons, allowing you to rip through waves of enemies extremely fast. Use this to your advantage to down scouts before they can retreat.
With the strength of the light machine gun combined with the large magazine size, the M739 can serve as a portable turret. While participating in game types such as Team Slayer or Capture the Flag in which vehicles are involved, a teammate can ride on the back of a Mongoose with the SAW; converting the Mongoose into a downsized Warthog. Another advantage to this method is the increased looking mobility which is twice than that of a Warthog turret. You should only do this once any anti-vehicle weapons are in your control, or else you might be giving the other team a free double kill.
This same priciple of a "mobile turret" can be employed defensively as well. An M739-armed player can effectively single-highhandedly protect an objective from any small assaults and seriously cripple larger ones, allowing the rest of their team to focus on dealing with the enemy and their own objective.
The SAW's reload time is very long in comparison to similar loadout weapons, making it imperative to briefly withdraw from combat and find cover before attempting to reload, and to manage ammo consumption in dense combat scenarios. The reload is also the same if the magazine is empty or not, meaning that there is no penalty for unloading the entire mag.
In the campaign, the SAW first appears towards the end of Blue Team.
In Warzone, the standard SAW is effective for guarding Armories and Cores. It also appears with two additional variants in Arena and Warzone:
Appetite for Destruction: an improved SAW with 50% larger total ammo capacity and Stabilization Jets to almost totally eliminate vertical recoil, allowing shots to stay on the target.
The Answer: an advanced SAW that can and will exterminate anyone foolish enough to approach you in seconds with airburst-fused high explosive rounds that have little, if any, range drop off. It can also be found in the campaign level Genesis, making it useful against the two Warden Eternals and their Promethean minions.
Either weapon, when paired with a Damage Boost, can be used to destroy anything up to and including light aircraft.
Reloading from an empty magazine takes the same amount of time as a partial one, as in Halo 4. This is especially important with The Answer, as only five or so rounds are needed to kill an enemy Spartan. Only reload when near the bottom fourth of the magazine.
A SAW paired with a sniping weapon such as the Sniper Rifle or Binary Rifle is arguably one of the best ordnance weapon combinations for dealing with infantry, as it allows the player to swiftly eliminate enemies at all ranges of combat.
The SAW appears as a power weapon on several maps, including Mercy. Controlling it is important, but secondary to more impactful weapons such as the Sniper Rifle or (SPNKr)Rocket Launcher.