All the three point mounts will loose zero sooner or later because the receiver "squirms" at each shot. Most will not mount close to zero because the clip slot dovetail tolerances are not that tight even on GI receivers. I recently examined a USMC DMR rifle built at Quantico and the three point mount was tack welded to the receiver and dovetail in a number of places, not very neatly either. Purists would be mortified. The Marine to whom it was issued told me that was the only way they could maintain zero. There is a reason John Garandicon designed the single screw mounting point. It always squirms back to the same place. The problems with single screw mounts has been solved by Bassett. His mount puts cylindrical rod sections into the slots, so they do not bottom out. His mount does not draw down against the receiver flat, but pulls against the screw with a set amount of torque. The Bassett does not shoot loose, does not block the open sights or interfere with ejection and is very light, which reduces recoil and recycling strains. I use low Burris alloy tactical rings on the Picatinny Bassett with Leupold 3.5X10X40.