The Ruger Weaver-Style Scope Base Adapter (brand part no. 90228) is a factory drill-and-tapped base built to fit the Ruger Mark I, Mark II, Mark III, and 22/45 rimfire pistols. It installs on the pistol’s existing factory-drilled and tapped mounting holes, so no gunsmithing or additional drilling is needed. It measures 4.5 inches long and converts the pistol’s receiver to a standard Weaver-style rail, opening up mounting compatibility with the wide world of Weaver scope rings rather than Ruger’s proprietary ring system. Ruger anodizes the base in black to match the pistol’s factory finish, and machines it from aluminum to keep it light on the front of a rimfire handgun. Because it does not accept Ruger’s own scope rings, buyers need a set of Weaver-style rings to complete the mount, sold separately.

Key Specifications

• Ruger Mark I/II/III and 22/45 Fit is a factory drill-and-tapped fit for these Ruger rimfire pistols.
• Factory Drill-and-Tap Installation uses the pistol’s existing mounting holes with no gunsmithing required.
• 4.5-Inch Base Length spans the receiver for a solid, secure mount.
• Weaver-Style Rail Conversion replaces Ruger’s proprietary mount with an industry-standard Weaver pattern.
• Aluminum Construction keeps the base lightweight on the front of a rimfire pistol.
• Black Matte Anodized Finish matches the factory pistol finish.
• Requires Separate Weaver-Style Rings since it does not accept Ruger’s proprietary scope rings.
• Single-Piece Base Design ships as one adapter with no rings included.

Frequently Asked Questions

What pistols does this base fit? The Ruger Mark I, Mark II, Mark III, and 22/45.

Does it accept Ruger scope rings? No, it requires Weaver-style rings, sold separately.

How long is the base? 4.5 inches.

Buy the Ruger Weaver-Style Scope Base Adapter

Mount a scope on your Ruger rimfire pistol with this factory Weaver-style base adapter from our scope bases selection. Order online and we will ship it straight to your door from our Lubbock, Texas gun shop.