Attractive wax cast steel rear sight, adjustable for elevation using the center screw. The standard 3/8" dovetail base is covered by the sight. Enlarge the square slot as needed.
The dovetail base measures .375" as-cast, a crisp clean casting along the edge grooves. Deburr the bottom of the dovetail base, removing the casting gate from this hidden surface, until the sight fits your slot.
The dovetail base and the skirt which conceals it are .600" wide. The sight is 3.135" overall length, and the rear blade stands about .440" above the barrel, when adjusted to lowest elevation. You may reduce and reshape the sight blade, hand filing, if needed.
Drift this sight right or left to align windage, and trim the sight blade (or front sight blade) to zeron the elevation. Then you can make fine adjustments for longer range, using the screw.