Have you looked at these ,I use this one on my N550 http://www.ebay.co.uk/itm/1-Inch-25mm-1-Ring-Weaver-Scope-torch-flashlight-Rail-Mount-20mm-picatinny-UK-/390860677169?pt=UK_SportingGoods_Hunting_ShootingSports_ET&hash=item5b011ca031
the same one I used on my n550 everything lined up perfect with that mount