^ This.
OMA is meant to be switching to other classes (From Sniper Class to SMG Class etc) NOT to refill your tube. I dont know why they didn't patch it (aIW did that a long time ago)
Tubing takes no skill, is annoying, makes you rage,destroying your mouse, keyboard etc, and other things so it would be very nice to remove OMA Tubing in SnD
By the way, Who tubes in SnD? Ground war is way better to tube.