What's the deal with machine guns? I find that it's pretty easy to snipe the gunner/get sniped if you are the gunner, and that the rifles have so much long range killing potential that the suppression from the MG is not really needed.
You really serve as a distraction, as most enemies are going to prioritize you while your teammates (hopefully) get into good positions to kill them. The goal isn't to kill enemies(unless you see a group) but to keep them scared to poke their heads out, so your rifles can focus on fewer enemies at a time. The mgs really shine in places with distinctive cover, like urban areas, where enemies will mostly come from one direction and you can see anybody that pops out. Best example, the beginning of Bridges of Druhzina is shit for MGs because the tall grasses and craters conceal enemies really well. But once you get to the urban part and the second bridge, it is much easier to see enemies move around between the rubble and allows you to focus on keeping multiple people suppressed.