Even if this isn't in the original Fallout world I think it would seriously balance the huge differences between tank minigun powerbuilds and tactical smallgun weapon builds.
Ok, depending on hex, skill in weapon in use, type of weapon, etc... When in cover you will get a damage resist modifier. ( Example: one person is 5 hexes away from another in cover, and that character in cover will recieve a 10% bonus in damage resist. You can hold the left mouse click on an object and click on a figure showing a person and an arrow point to a wall with a character right on the wall in crouch or stand postion. Once you let go, your character will run immediately and hug onto the wall or car or whatever. once you leave one hex from the object you are out of cover and will not recieve damage resist. Of course there will need to be angle counters to this. Flanking, ( No need for description ) will cause a damage modifier in terms to the person shooting the person in cover from an angle where they are totally exposed. 5 hexes away , player smallgun is in cover, big gunner fires, smallgunner is hit and 10% modifier to damage is added due to flank.
Now the only downside to this for many players will be that holding a large two-handed weapon would make it impossible to be in cover so the smallgunners who have always been nerfed in comparison will have at least one advantage over big gunners.
Comments, suggestions to add, etc...?
This isn't a VERY well thought out suggestion i know but it just came to me.