The gun does not come with a scope mount. It is a rail.
You will have to select the proper mounts to accomodate the scope of your choosing. You want to keep the scope as low to the barrel as possible.
I strongly suggest that you remove the screws that secure the rail and Lock-Tite them so you are always assured that the rail is dead nuts secure.
No matter what anyone says I will suggest, from alot of experience, a Simmons straight 4X scope (x 32mm). I have the Pro-Diamond models on all of our USH's and other slug guns. Have never had a failure of any sort. Great in low light. And the Pro-Diamond is a benefit also.