SGA is the most ridiculous MG in the game. It basically hits every shot, because those that it misses it refunds, and it can fire your full load of heavy ammo in a crazily short time. For jobs that require continuous damage for a period of time (like dropping shields on something with super fast shield regen) or for maximising the usefulness of an area denial bullet hose, it's immense. The recoil is very high though, and if you are good at recoil control you will find your ammo doesn't last very long. I like it for making Crota/Talnok kneel. I guess it's probably still awesome at Oracles and for heavy boss damage when you only have a short exposure window.