Sadly no Ionic Light Machine gun in the game. All that said, don't go by the DPS counter I find. Depending on your perks actual damage you apply can be insane. Good example is the Ionic Sword, my DPS shows 1k DPS in tool tip, however in actual use always hits for over 10k damage.
I find cold blood tree synergises with everything and makes everything insane period if you equip your body with crit chance / damage. Try that with the LMG and you will mowe everything down and most hits will crit and crit hard. Still not to level where you can one shot cyber psycos on hardest difficulty like tech weapons or assault rifles when levelled, but will kill everything in seconds anyways.