Yeah people don't seem to shoot the arms on Assaults much.

I often run a heatsink or two on the same arm that has the LLs and extra UAC5 ammo on the same arm as the UAC5, the thinking being that if I lose the arm and the weapon then the loss of the corresponding heatsink or ammo is fine.

i7-7700k@4.5ghz, GTX1080Ti,BenQ XL2420G-g-sync,Oculus Rift