You don't have to place the nvg optic in front of the ACOG/4x to use it. It is difficult to do with those particular goggles(which are outdated and practically non-existent in the U.S.) which is why I noted the pvs-14. Very few units in real world actually use those goggles with the single centered mono tube unless they bought them from a Cheaper Than Dirt catalog. I can assure you that you can in fact look through and use a 14 mounted on your helmet and see through an acog. It may not be optimal (it's not, because it is less "fuzzy" and doesn't pick up the light as well when front mounted) but it does work. Supposed to be the future right? Why still using 80's nv mono tube goggles and not something newer/better i.e. dual tube detach or quad tube? Must be a way to cut down clarity when looking through optic in game to compensate. Maybe make it darker and limit the distance to 200 meters or so instead of just not simulating it altogether. Or do the above stated of allowing a monocle attachment. It shows dual tube on helmet but the ole' nvg in inventory.