User blog comment:Callofduty4/Black Ops II Multiplayer Reveal released!/@comment-32237267-20120808021558/@comment-4861962-20120808032558

There was a leak back in March-April that said an XRay scope was a killstreak you attach to your weapon after you've earned it.

Also, there was a killstreak called Item Packages, which cintained things like Ammo and Special weapons, so maybe you can use an item package to get teh Storm PSR and get 4 kills to unlock the Xray scope for it.