Let's think about it more rationally:
Ironsights can't really affect the gun at all, but let's say scopes - scopes would give you x# zoom, BUT you would get a little bit disoriented because of the zoom.
The grip could give you less recoil, but less accuracy or so?
Buttstocks would basically give you less recoil, but less accuracy
Silencer would silence the gun & Muzzleflash, but would reduce DMG.
etc.