By Mark V. Lonsdale, Training Director STTU
The goal for today’s testing was to evaluate whether AD scope mounts returned to zero after being removed and replaced. For the testing we used a Leupold VX-1 2-7X, 1″ tube, in the AD-Recon 1 STD mount, and a Leupold Mark 4 3.5-10X, 30mm tube, in the AD Delta-C 30 STD mount.
Two Leupold scopes and AD mounts used in testing
After zeroing, the testing was done at 100 yards utilizing relatively inexpensive American Eagle 62 grain ammo; so the expectation was not sub-MOA groups, just consistent, repeatable combat accuracy. This could be defined as staying within a 3-inch circle at 100 yards. Future testing will be done with Federal Match ammo.
For the testing, we shot a 5-round group on one target with the Leupold VX-1 set on 7X, then changed scopes and mounts and shot a 5-round group on another target with the Mark 4 on 10X. We then replaced the VX scope and shot another 5-round group on the first target; followed by changing to the Mark 4 and shooting another 5-round group on that target. This was repeated three times.
Leupold Mark 4 mounted on the American Defense UIC Mod 2 with AD-Delta-C 30mm mount
In all cases the groups stayed within 0.5″-1.0″ of the previous groups and stayed well within the 3″ circle.
In addition to the positive cam locks and precision machined rails, one of the reasons that the American Defense mounts have a high level of return-ability can be attributed to the thick cross bolts that all but fill the slots in the rail (see pic below). Cheaper mounts use thinner bolts that allow the mount to move back and forth.
Note the thickness of the cross bolts that contribute to a positive return-ability