Damage per second (all advanced)
Heavy machinegun: 630
Assault rifle: 446.25
Rail rifle: 444.23
Assault rail rifle: 450
Assault combat rifle: 440

At advanced tier, automatic rifles do about 440-450 damage per second, while an advanced HMG does 630; around 190 more damage per second. This may lead one to believe that this justifies the short range of the HMG, but the numbers are misleading. The actual DPS is pretty poor most of the time because despite having the circle reticle on the target, the amount of bullets actually hitting will be very low because only where the center dot is aimed on will do damage (proof). This makes the automatic rifles much more useful, even at the close range where the HMG actually operates the best. The HMG sucks, and that is why heavies are more successful with light automatic weapons.

On top of the inability to deal damage effectively, there is the horrible issue of range. The optimal range is around 30 meters, and effective range is about only 50 meters. Some would say a heavy dominates at "point defense" despite its poor range, but an AR can be just as effective with higher optimal range, and much higher effective range, 65 meter effective range, while the HMG only has 50 (and the AR is the shortest range automatic rifle). This is important for the future; there will be a laser and a plasma heavy weapon in the future, and the plasma weapon will be the shortest range heavy weapon (plasma tech is short range). The HMG is a projectile weapon, projectiles are meant to be useful at mid-range.

Solutions

Make bullets fired spread out evenly in the aiming reticle circle of the HMG, instead of just on the central dot. This would make damage application much easier, and ultimately make the gun more effective. This would make using the HMG at longer ranges more effective since we won't have to aim a tiny dot.

Increase effective range from 30 to 35 (not much needed), and increase the effective range to 60 meters. This small increase in optimal range and effective range is pretty modest. Projectile weapons are meant for mid-range, the future unknown Gallente plasma heavy weapon should be the the close range heavy weapon.

That's it. Bit more range, and distribute the bullets evenly in the reticle. Make the HMG a weapon worthy of being restricted to heavies only.

Honestly, if you just made all the rounds hit inside that little circle, crouching would give it the ability to not only hit but suppress at medium range.

If I know I can kill you faster than you can kill me, your suppression is worthless, I will just out gun you.