I suggest further differentiating AST rifles from each other for the sake of having unique weapons with their own purpose and effective range. This assumes that you leave the current weight, muzzle velocity, and accuracy values alone:
MOLD - WS lock. ROF 14 (same as handguns).
76RA (and HITEN)- Ammo increased to 200, Mag reload decreased to 60, ROF 20.
84RA2 - ROF 14, mag reload increase to 150
GAST - ST lock, maybe ROF of 17? Mag cap increase to 20.
05RLA - Increase ammo to 90 or Increase ammo to 75, but reduce mag reload to 90. ROF should be around 25-27 in either case.
This way, you've got your 76RA as your all rounder, lots of ammo but with heavy weight. RA2 as your long range, fire-from-cover AST rifle that works better at longer distances compared to close range. GAST becomes your close range AST rifle. While the MOLD becomes a hybrid MG/HG. Special mention for the RLA for being too heavy.
Essentially you've got a long range, high damaging weapon (RA2) that have lower overall DPS versus moderate damaging midrange weapons with higher rate of fire and DPS (GAST), and an easy to use rapid fire close range weapon (MOLD) that is only effective at CQ ranges. Think of the MOLD as a high-cap handgun with a higher ammo count, bridging the gap between AST HGs and true AST rifles. And then you've got a weapon that's good all around, but is pretty heavy (RA).
These aren't exact figures though, and may still need tweaking, but my theory is sound I hope.
What do you think?