When was the high standard .22 caliber Double-Nine Revolver Model r-101 made?

The High Standard Sentinel .22 Revolver is a line of firearms created from the 1950s to the 1970s, and they were originally sold by Sears Roebuck under the J.C. Higgins brand. The Double-Nine R-101 series is a western-style firearm that was offered to the public in 1958.

Causing confusion among collectors, the Double-Nine R-101 was first sold as the J.C. Higgins Ranger Model 90. The Double-Nine's original specs include a high-tensile carbon-steel .22 barrel, anodized aluminum frame, single-stroke ejection for reduced jamming and a swing-out counterbored cylinder. The R-101 series is the second generation of the Sentinel line and features modified hammer and trigger mechanisms for increased performance.