The DMR is the starting weapon for the multiplayer modes of Slayer Pro, SWAT, and several others. It is also the starting weapon in all MLG gametypes. It has a 15 bullet clip and can take out a Spartan with four shots to the body and one to the head. With an Elite, it takes 5 shots to the body and one to the head.
The DMR is confirmed to be making a return in Halo 4 as a mid-to-long range counter to the Battle Rifle.