Edit: If you think if its simulation - fine - just add "often broking gun in fight" or "repair the sniper rifle lock while TC fight" now you see - its not real guns simulation
it is, check this out.http://www.army.mod.uk/equipment/support-weapons/1461.aspx
what about a custom menu, if you got few guns, you can open menu and "merge" them, by a repair, somewhat a system like in Fallout 3, so you dissasemble them and useful parts put into one gun? but only if you got SG/EG/BG Crafter profession (on guns which are craftable only by prof.)