Great game, really, well done on this so far!
The zoomed optic sensitivity should not be tied to the standard ADS one. A suggestion from how battlefield does it, they have sensitivity sliders per zoom level. You don't need all of that since the Marines only had so much to work with in the first place. So I would suggest a zoom sensitivity multiplier or scalar for point shooting vs iron sight/acog zoomed shooting. Currently I'm dropping my sensitivity low enough to handle the acog but when point shooting it's too slow. So I've had to compromise a bit between the two which ruins the experience a bit.