I was thinking something along the lines of Heavy ion cannon
Basically it's just a suped up bus gun, but in a heavy port.
The reason something like this is needed is because of the difficultly early on to raise you Heavy weapons skill, so it need not be the best gun ever, just something usable.

hmm I have never had difficulty raising my hvy weapons. However another L port energy weapon would not hurt.

I agree!

/givemoney Devs 2c