I should have asked if a 4001 would be too low since some of the cheek pieces on the pictured AT-X's appeared lower and when I zoomed in on the pics they were all 1.5" mounts. I won't be running NV on this rifle.That gun was setup with a tall 20moa pic rail like a gun would be setup to run night vision with the forward rail on the bridge. You can also use a lower pic rail and lower mount