Are you aiming for the head? That makes a HUGE difference in time to kill. When you see their shields drop, all it takes is one shot to the head with a precision weapon and they will go down. Get in the habit of aiming for the head as often as possible.
Generally speaking autos are weaker than single shot weapons.
You cannot suddenly get real good at halo like you can other shooters.
POINT TO KEEP PLAYING: if you get good at halo youll be a beast/godly in other shooters
Most halo players complain that other shooters are way to easy or reward camping tactics. We do play other shooters and when we do were probably that guy going 20-0