Oh Heretic you evil man, quoting me while I am still editing (and doing ingame
!!science!!(sorry, dwarf fortress habit

)).
I generally agree with you, especially the part about the range. It is the mech/tank weapon with the lowest effective range (apart from flamers), which makes the whole weapon kinda hilariously bad.
Also I do think it needs a buff concerning its ammo, look at it that way: 4 guns need to fire roughly 50% of their bullets to core a light mech, so you'd have to fire
2 full magazines if you were to use a single one. This is pretty pathetic for one of the most advanced weapons in the classic BTU.
Even if the magazine size was doubled it would still need a full reload to kill a cougar, which is bad, but at least not that stupid.
Long story short, I don't think the weapon deals enough damage for each ton of ammo.
Possible idea to fix that would be to simply raise the ammo/ton, but if that is not possible/wanted (hey, IIRC UACs do also get more ammo then normal ACs, so why not the RAC, too?), one could also raise the damage dealt per bullet, while at the same time lowering the time it takes until it overheats, so that "long-term-dps" stays the same.
Also:
Ages ago I suggested to add
different weapon modes, especially for cases like the RAC. Make the current weapon with less spread the x4 mode, and add the x6 mode, which overheats in half the time, but deals considerably more damage per second, while also spreading like our current weapon. That way you'd have a strong melee oriented burst mode, which is good for quick fights, like hit and run, and one mode that has better dps on the long term, and also a much better effective range.
This would not fix the "damage/ton of ammo" problem, but at least it would make the weapon a little more desireable as a secondary weapon system.