For myself the Base Gatling laser has a base damage of 189 per shot while the Base Gauss has 552 per shot. (I assume the instigating for each each have double that) but the Gatling becomes so OP in VATS. Each Action point fires something like 10 shots in VATS. When you activate critical it applies critical to each of those 10 shots (can be abit more or abit less). Long story short with 2.5 critical damage each shot in Vats for the Gauss does 1380 (or 2760 as I believe VATS charges each shot), while for the Gatling it does about 4725 per action point. Unless my Math is way off.
Either way both are OP everything including Mythic death claws, Super mutant Primes and warlords are downed in one hit on survivor.
Seeing those figures makes me wonder what the instigating versions / double shot version would do

Moreso if you fire the gauss from sneak attack + silencer you can attach with sandman and Ninja perks