From 11 mm Dovetail to 20 mm Picatinny – Two-Point Bridge Adapter

Many air rifles and .22LR rimfire firearms come from the factory with an 11 mm prismatic (dovetail) rail, while the vast majority of modern scope mounts, rings, and accessories require Picatinny / Weaver compatibility. This adapter bridges that gap – a mechanically straightforward but precisely machined solution.

Design and Construction

The adapter is manufactured from CNC-machined aluminium alloy with a black anodised finish. The production process ensures accurate rail geometry and parallel surfaces, which matters for holding zero over time. The anodised finish is more wear-resistant than painted alternatives and produces no unwanted glare.

The bridge-style design clamps to the 11 mm rail at two points. This is particularly important on magazine-fed air rifles and .22LR platforms where the position of the magazine port makes conventional one-piece bases impractical – the bridge spans the magazine port without covering it or interfering with case ejection.

The 140 mm clamping length provides stable two-point support even when the firearm's factory rail is only 100–120 mm long. This is a real engineering constraint on many air rifles and rimfire firearms, and one that this adapter is specifically designed to address.

Rail Geometry and Positioning Options

The upper 20 mm Picatinny / Weaver compatible rail is 174 mm long and features 14 slots. This gives ample freedom when positioning rings or a one-piece mount, allowing precise eye relief adjustment – even with longer-tube scopes.

The 24 mm height represents a high-profile configuration: the optical centreline is raised relative to the firearm's rail. This is an advantage with larger-objective scopes where clearance beneath the tube is needed. It does mean, however, that you should verify the mounting height suits your specific firearm-optic combination before installation – ergonomics and cheek weld can only truly be confirmed by a physical test. If in doubt, get in touch and we will help.

Technical Specifications

• Overall length — 174 mm
• Clamping length (dovetail base) — 140 mm
• Height — 24 mm
• Top rail width — 20 mm (Picatinny / Weaver compatible)
• Number of slots — 14
• Bottom mount — 11 mm dovetail (prismatic rail)
• Material — aluminium alloy, CNC machined
• Finish — black anodised
• Weight — 64 g

Intended Use

This adapter is primarily intended for air rifles and .22LR rimfire firearms equipped with a factory 11 mm prismatic rail. The bridge design is especially useful where the magazine port position rules out a one-piece base. It is not designed for high-recoil centrefire calibres.

If your firearm has an 11 mm rail and you want to fit Picatinny-compatible optics – this is a straightforward, stable, and lightweight solution.

Who Is This For?

This adapter is recommended for anyone who wants to use modern Picatinny-compatible optics on an air rifle or .22LR firearm with a factory 11 mm dovetail rail. It is especially practical on magazine-fed air rifles, where the bridge design clears the magazine port. The 174 mm length and 14 slots provide generous positioning options, while the 64 g weight keeps the setup light.