Windage-adjustable rotary dovetail bases are very traditional, lightweight and attractive. One-piece bases usually have only one mounting screw in the rear location, which compromises strength. Offsetting this weakness, both rings can be horizontally boresighted to almost any rifle bore. The rings secure the scope tube using two screws per ring, which is adequate because the rings made of machined steel. Use of RingTrue™ tape will insure that these rings adequately grip the scope tube.
Two-piece bases attach with two screws each and therefore offer a stronger attachment to the receiver. Two-piece bases may require shimming or bedding to minimize any vertical mis-alignment between the rings. When lapped, rotary dovetail bases offer a strong and stress-free scope mount.
Double dovetail rings and bases allow the rings to be aligned to each other, but not necessarily to the bore. While the bases are more slender, the lack of windage adjustment limits the benefits of this design.
Millett rotary dovetail rings are made from cast steel and have corrugated ring surfaces that are designed to be used with thick liner tape. They are inferior to either the Leupold or Redfield equivalents for reasons discussed below (see section on Millett Angle-Loc rings).