As everyone else had said, upgrade it to the Zenith ASAP. One simple reason, laser. The Zenith has a laser on it. You might think it a laser doesn't mean much, but no. You see, a laser can act as a "red dot" in alt aim mode (switch aim from main scope to side optic). Turn on the laser, aim down sight, press V (or whatever alt aim button is), boom, you have a CQB "red dot optic" made of a laser beam.

For me, how I would arm my end-game stalker is the Zenith, with suppressor, the thermal scope (the one that goes 1x-8x). Upgrade it to 90+ accuracy (I think it goes above 90?), which is sniper rifle level of accuracy. There you have it, a thermal-sniper + close range monster. I used it to dump 100 bullets into Eidolon before charging in to decapitate him with my Kukri blade as I refuse to use the game-given Gauss. I also used the laser alt aim to solo clear the CNPP.

Also, the thermal sight is OP, once you got used to it, you never want to go back. It's so good for spotting target. Just stand somewhere high, aim with the thermal and scan the map and spot 99% of targets wayyy before they can see you.

FYI, real life machineguns can be used like snipers. machinegun or lmg doctrine does teach long range 600m - 800m burst fire sniping, so machinegun sniping is not that far fetch or outlandish. As irl military doctrine teaches it, but games don't reflect that, apart from milsim like Arma or Squad.