Arisaka Defense Offset Plate, 1913 Picatinny Rail Adapter, 40 Degrees Only

The Arisaka Defense Offset Plate is a modular 1913 Picatinny rail adapter designed to mount a red dot sight at an offset angle on your AR15. This 40-degree offset configuration positions your optic to the side of your rifle's top rail, allowing you to keep a primary scope mounted centrally while running a secondary red dot for close-quarters engagement or rapid target acquisition. Unlike fixed offset mounts, the Arisaka system uses interchangeable plates, so you can upgrade or swap optics without replacing the entire mount—just purchase the plate that matches your specific red dot model.

The modular design means the base stays on your rifle while individual optic plates can be swapped out as your loadout evolves. Whether you're running an Aimpoint Micro, Trijicon RMR, Holosun, SIG Romeo, or any of a dozen other popular red dots, there's a compatible plate. The base and plates can also be reversed, giving you flexibility to mount on either the left or right side of the rail depending on your setup and dominant eye.

Built tough for real use, the mount is CNC machined from 6061-T6 aluminum and hard coat anodized to MIL-A-8625 Type III specs. It weighs just 1.9 ounces, keeping your rifle light and handy. Installation takes minutes—the base clamps across three Picatinny slots with twin recoil lugs and uses included Torx Plus bit drivers for a solid, repeatable zero. At only 1 inch long and sitting just 0.180 inches above the rail, the Arisaka offset plate keeps your setup compact and co-witnessed properly when your rifle is canted to use the red dot.

Key Features

• 40-degree offset angle for secondary red dot mounting on AR15 Picatinny rails
• Interchangeable optic plates—upgrade or swap red dots without replacing the entire mount
• Reversible base and plates for left or right side mounting
• Machined 6061-T6 aluminum with MIL-A-8625 Type III hard coat anodize
• Lightweight at 1.9 ounces (base only)
• Clamps securely across three Picatinny slots with twin recoil lugs
• Includes IP20 and IP27 Torx Plus bit drivers
• Low profile: only 1 inch long, 0.180 inches above rail

Specifications

Frequently Asked Questions

What red dots are compatible with the 40-degree Arisaka offset plate?

Compatibility depends on which individual optic plate you pair with the base. The base is universal; plates are sold separately and designed for specific red dot models. Common compatible sights include Aimpoint Micro, Trijicon RMR, Holosun 407C/507C/508T, SIG Romeo models, Leupold Delta Point Pro, and many others. Check the product listing for your specific red dot model to confirm the correct plate number.

Can I use the Arisaka offset mount on the left side of my rifle?

Yes. The base and optic plates are reversible, allowing installation on either the left or right side of the Picatinny rail depending on your preference and shooting style.

What if I want to upgrade to a different red dot later?

The modular design lets you keep the base mounted on your rifle and simply purchase the correct optic plate for your new sight. Plates are sold separately, so you only upgrade the plate, not the entire mount.

How does the Arisaka offset mount co-witness with my primary scope?

When your rifle is canted to align with the offset red dot, the optic remains centered over the bore and maintains a lower 1/3 co-witness height with a properly mounted primary scope.