Quick Tip: Mounting an Offset Optic
In this Brownells Quick Tip, Caleb shares his method for mounting an offset red dot sight on an AR-15 platform. Whether you're shooting left- or right-handed, getting your offset sight in the correct position is critical to maintaining zero and fast target acquisition.
Why You Shouldn’t Mount Optics on the Handguard
One of the most important fundamentals is avoiding the handguard when mounting optics. Mounting a red dot on the handguard may look convenient, but it won't hold zero if the handguard is bumped or flexed. Always mount your offset red dot to the upper receiver for best results.
Ideal Placement and Scope Interference
Caleb mentions that ideally, the offset optic would sit closer to the shooter's face, but the main scope usually occupies that space. Some rings, such as those from Midwest Industries, allow you to mount a red dot on top. However, for long-range rifles with tall turrets, top-mounted red dots often won't clear the height of the turret, making offset mounts a better solution.
Choosing the Left or Right Side for the Offset
Since Caleb is a left-handed shooter, he mounts his offset red dot on the left side of the rifle. Right-handed shooters would mount it on the right side. This positioning ensures the red dot is properly aligned in your line of sight when the rifle is canted for close-range shots.
Using the Vortex Offset Mount
The featured mount in this setup is a Vortex offset plate that comes ready for DeltaPoint Pro and Aimpoint Micro pattern optics. The plate is labeled for orientation, but it can be reversed for left-handed use. Torque specs are labeled directly on the mount, simplifying installation.
Reconfiguring the Mount for Left-Handed Use
Caleb demonstrates removing and reversing the mount to fit the left side. The process is straightforward, and all necessary torque specs are clearly marked on the hardware. Once reversed, he re-tightens everything using a torque driver set to the recommended 18 inch-pounds.
Mounting the Offset Base to the Upper Receiver
The mount is installed onto the upper receiver rail—not the handguard—using the included screws and torque specs. In this case, 30 inch-pounds is the recommended torque setting. Since Caleb is using a quick-detach scope mount, he adjusts one of the levers to clear space during installation while ensuring his primary optic stays zeroed.
Mounting the Red Dot to the Plate
The Leupold DeltaPoint Pro is mounted to the Vortex plate using the original screws that came with the optic. Caleb tightens them down using a smaller T15 Torx bit and torques them to 12 inch-pounds as recommended.
Final Setup and Function Check
After mounting, Caleb powers on the red dot to confirm functionality and alignment. Everything checks out, and the red dot is in the perfect position for quick transitions when shooting close-range targets with a long-range setup.
A Flexible and Reversible Offset Mounting Solution
The Vortex mount offers a simple, reliable, and reversible platform for adding a backup red dot sight. It's an excellent option for competition shooters, hunters, and tactical users who need fast target acquisition without compromising their main optic.
Closing Thoughts
If you're mounting an offset red dot on your AR-15, following these steps will ensure reliability and maintain your optic's zero. For right-handed shooters, follow the same procedure on the right-hand side. And don't forget to reset any quick-detach levers or components you adjust during installation.
