1) The scope ocular shoulder rests on the rear side of the rear ring, and the front side of the rear ring recoil lug rests on the front side of the rear bridge recess. Here, a Schmidt & Bender 1 1/4-4 x 20 with 30 mm tube in Alaska Arms rings:
Note: this may not be possible with all scopes. In some scopes, there is no ocular shoulder, and resting the scope against the rear ring would block (and likely damage) the magnification ring...
