Has anyone else been using this beast of a weapon? I used to hate using it as it could easily be outclassed by any of the other rifles, but now it seems to be much more effective at close quarter matches than the battle rifle. I think what partially helps is the rate of fire, which puts a lot of pressure on the reticule of your opponent, and makes it harder for them to hit you if you continue to lay down shots.
I have been using it since day one of halo 4 
Dude, where the hell have you been?
Since the TU, Carbine and BR basically dominate most high-level play. DMR has been strictly regulated to long-range due to the fact that it can’t really win in a mid-range fight unless its opponent is limited, and autos still can’t do much out of their niche.
I do better using the DMR or BR, and it helps when everyone else uses those weapons because there is ammo lying around every time you get a kill, but using an underdog like the Carbine is immensely satisfying to get kills with.
The BR and at times the Carbine go toe to toe with AR users a lot of the time, and at times against a shotgun. It’s rate of fire needs to come down a small hair, it will still excell at mid-range (as intended) so don’t start flaming, but the AR needs more breathing room.