Beowulf TCR + Binary Trigger [Read Desc for more info]
There is no damage penalty or Head/Torso/Limb multiplier penalty to using this attachment, using 5.56 + binary trigger basically turns this DMR into an assault rifle.
The binary trigger is under OTHER, ACCESSORIES.
The build I was using was:
Reflex Sight
Squad Barrel
Verticle Grip
Binary Trigger
5.56x45mm