Being that there is going to be a move to more complicated damage modeling on vehicles, it is interesting that the .50 cal TTL (time to live) on the M16MGMC is held to the same distance as the buff guns.
While the M-16 is already extrememly vulnerable, but it's effect gunnery distance is about half as much as it's real life counterpart. It could probably use TTL slightly over the tracer life...but going for the 3200 mark may be a little to much for that many .50 cal shells. The very high dispersion rate at very long ranges would have to be taken into consideration when adding TTL.
As to why gunners were instructed to open up at an estimated 5000-7000 yards, beats the heck outta me