Sako rifles are designed to use Optilock scope mounts and rings -- which are also produced by Sako. Sako rifles are generally sold with the scope mounts, along with the tools required for installation, included. Unlike most other scope-mounting systems the Optilock system requires that you first attach the scope-rings to the mounting bases before you attach the bases to the rifle. Optilock bases slide onto the groves that are precut into the upper receiver of the rifle and are secured by retention pieces that slide into the side of the mount.
Make sure the rifle is unloaded.
Install the scope rings onto the mounts by screwing in the supplied screws from the bottom of the bases.
Slide the mounting bases onto the slots cut into the sides of the rifle's upper receiver. Position the mounts as desired, place the retention pieces into the right sides of the bases and tighten them into position with the supplied screws.