It would be cool to have weapon jamming or malfunction present in the game. it would not take much to do as maybe you could have the jam be the same procedure which is to reload the weapon. A icon for a weapon jam can show up and the user could reload or use the action menu to solve the jam. For me personally, the jam should be set to a rare presence as it would be annoying to have it frequently. but the occasional jam would add intensity of trying to get you gun back into battery to be ready for the fight.