When playing with the Mantis (as I am lent to doing extensively on the "Two Giants" Spartan Ops in Episode 3) I find that the machine gun overheats constantly. In past games, I found out after quite some time that there was a benefit in accuracy to "pulsing" the certain full auto weapons - particularly in accuracy. For the Mantis, I'm also interested to know if pulsing it will extend the amount of time before it overheats. Experimentally it seems like it may be extending the overheat time, but I can't really tell what other affect it may be having (reducing DPS, for example). Is there a benefit to pulsing, or am I fooling myself?
I went into Valhalla on Forge mode to run some tests, and here are the results. I hopped in the Mantis that spawns on the beach, and aimed at a Rhino which I spawned. The "medium distance" tests were done with the Rhino at the first ridge, near the cave on the right hand side as you're facing away from the beach. The "long distance" tests were with the Rhino on top of the Spartan Laser spawn (on top of the ridge midway between the two bases). When I was pulsing, I was holding the button down for a few seconds and then letting it go, but not long enough for the gun to fully cool back down. Slowly, the gun started to heat up, but I typically destroyed the Rhino prior to it overheating.
The machine gun takes approximately 4.7 seconds to go from "cold" to "overheated." Once overheated, it will cool back down and begin firing in 3.5 seconds. If you stop just short of overheated, and wait until the heat has completely dissipated, this takes 4.2 seconds.
Therefore, it's faster to let the gun overheat if you wish to get all the way back to cold again. However, you can't fire while the gun is cooling from overheated.
Firing at the Rhino from medium distance, I destroyed it in:
Not a lot of difference here, although keeping the gun from overheating is advantageous, since I could react to other threats while dealing more damage overall.
From long distance, I destroyed it in:
Clearly there's an accuracy benefit here - as I noted above, the gun cools down faster from overheated, and at this level of damage dealt there's not that much of an effect from having to wait the entire cooldown period.
I would suggest that if you think you need to fire on a distant target (further than 1/4th the way across Valhalla), definitely pulse the gun. If you're firing a short distance at a soft target, (someone on foot or perhaps a ghost) it really doesn't make that much of a difference, however.