Offset Picatinny Rail Adapter 11 mm to 20 mm
Most air rifles and .22 rimfire firearms come factory-fitted with an 11 mm dovetail rail — a standard that has been present in the market for decades and is found on a vast range of firearm types. However, a growing proportion of modern optics, red dot sights and accessories require a 20 mm Picatinny (MIL-STD-1913) rail. This adapter bridges that gap, and offers an additional advantage: thanks to its forward offset design, the mounted optic can be positioned more easily to achieve the correct eye relief.
Why choose a forward offset design?
With a standard straight adapter, the optic mounting zone aligns directly with the position of the firearm's original rail. With the offset version, part of the Picatinny rail extends forward beyond the dovetail base plate — allowing the scope or other optic to be moved further forward. This is particularly useful when the factory rail is short, or when the magazine or bolt handle prevents the optic from being positioned further back. This situation arises regularly on air rifles and pump-action .22 firearms.
Construction and clamping system
The adapter body is machined from aluminium with a black anodised finish, providing protection against corrosion and mechanical wear. The base plate contacts the firearm's 11 mm dovetail rail over 110 mm and is secured with 4 hex screws — a notable feature in this category, where 2–3 screws are more typical. The 4-point clamping distributes the load evenly along the full length of the base, offering superior resistance to recoil.
A stop screw is located at the front of the base plate and engages with the recoil lug of the firearm's dovetail rail. This prevents the adapter from gradually shifting forward under repeated shots — a small but important detail that preserves long-term zero retention. The D-shaped slot visible at the rear of the rail serves a complementary retention function.
The upper Picatinny rail has a total length of 155 mm, providing sufficient space for longer scopes as well. The adapter height is 13.5 mm — worth factoring in when planning the optical axis height of the mounted optic.
Compatibility
The adapter fits any standard 11 mm dovetail rail — on air rifles, CO₂ pistols and rifles, .22 LR and similar rimfire firearms. The upper Picatinny rail is compatible with all MIL-STD-1913 (Picatinny) and Weaver-standard mounts, rings and accessories.
Technical specifications
- Rail type (bottom) — 11 mm dovetail
- Rail type (top) — 20 mm Picatinny (MIL-STD-1913)
- Total rail length — 155 mm
- Clamping length (base plate) — 110 mm
- Height (offset) — 13.5 mm
- Number of clamping screws — 4 hex screws
- Material — aluminium, black anodised finish
- Weight — 60 g
- Accessory — Allen key
Box contents
- Offset Picatinny rail adapter — 1 pc
- Allen key — 1 pc
Who is it recommended for?
This rail adapter is primarily recommended for air rifle and rimfire firearm owners who wish to mount modern Picatinny-compatible optics without replacing the factory rail. The forward offset design is particularly beneficial where a short factory dovetail limits positioning options. The 4-point clamping and stop screw also make it a solid choice for use on firearms with more noticeable recoil.
