Here’s another thought: Should different weapons have different spread patterns? Assault rifles, for example, would have upward recoil so the spread of an assault rifle should be vertical more-so than horizontal, creating an oblong shape rather than a circular one. The circular shape would work well with the heavy gun because it’s fired from the hip. I think for shotguns you should have something similar to the Player Unknown Battlegrounds mechanics, (now, hear me out for this one) where the red and orange circles are where the shot can go but the spread all lands in that area. In other words, if the shotgun is aiming slightly left of the circle then all the pellets will go slightly left of the circle. Mechanics wise, a single point would be decided and then a set pattern of shotgun pellets would be fired in a circle around that point.
Finally, the sniper rifle should be more accurate than other guns by quite a ways and while it’s already fairly accurate it’s pretty difficult to hit enemies at long range, as the sniper rifle is designed to do. Especially if you’re aiming for particular body parts. So I would suggest having just a single circle for the sniper rifle, either the size of the yellow circle or 75% the size of the current red circle. That being said, the sight range for soldiers is very far at the moment and even further for aliens. If this is reduced significantly in future the sniper rifle should be fine as is, since all confrontations will be at a much shorter range.