Here's a suggestion that I haven't seen a lot, 

What about weapon resting with snap cover? BF4 has a great cover system, but how about a weapon resting system that follows a similar control system? As in, if you can peek around or above a piece of cover (wall, hill, sandbag, etc.) you can also rest your weapon against that structure as well. Right now, Arma 3 (!) implemented something like this in its Marksmen DLC, I'm just wondering how hard it would be to implement this in the Unreal engine.