Apparently, before Destiny's original stuff was scrapped, the Khvostov 7G-02 could be upgraded to an exotic Auto Rifle called the Khvostov 7G-V2. It looked the same, other than that it had some yellow-colored parts attached to it. You could change the scope, aiming speed, and it had a perk that I don't remember. The description read "An ancient weapon, modified to its fullest potential. Use it wisely." I'm not totally sure on that, but you can look it up yourself. Pretty neat, eh?