You’ve got an optic on your GLOCK but now you’re realizing the need for a backup. Here’s the easy answer…

by Rob Reaser

If you’ve purchased a GLOCK with the Modular Optic System (M.O.S. optic cut) or have assembled your own GLOCK clone slide assembly that has been milled for an optic, you probably slapped on a low-riding red dot as fast as you could. You’ve had a blast shooting steel and paper, and maybe even picked up an optic-compatible holster to deploy your red dot GLOCK for EDC use.

Fun times, for sure. But once the “cool” of running an optic on the GLOCK simmers down a bit, the inevitable conclusion for most shooters is, “Man, I really need those open sights.”

Yes, you do.

Much as we enjoy shooting handguns with red dots, the pragmatic voice in our heads say, “Optics are great fun, but backup sights are absolutely necessary.” Batteries die. Electronics may fail. Guns drop and things break. In short, defensive guns need no-fail sighting systems.

The solution is simple. Swap the low-profile factory open sights with taller, M.O.S.-compatible sights. With M.O.S.-compatible sights, should the optic on your GLOCK ever falter, the taller front and rear sights are clearly visible through the optic, providing an aiming solution that will never let you down. And if those open sights also happen to feature tritium illumination, all the better for low-light use.

Some time back, we put together an optic-friendly slide for a GLOCK 17 based on the Rival Arms Faction Series slide assembly. Featuring a cool “Ready Red” distressed finish and a factory optic cut, it was the perfect candidate for TRUGLO’s Tru-Tec Micro Sub-Compact red dot.

Fast-forward. Time to install some open sights. To go along with the Rival Arms slide assembly, we selected Rival Arms’ M.O.S. height tritium night sights. We’ve used their standard-height sights for other projects and have been pleased with their solid construction. The tritium vials, secure in the machined stainless-steel housing, deliver exceptional visibility in low light conditions and the U-notch rear provides quick sight alignment.

Sight Installation

Remove the barrel and recoil spring/guide rod assembly from the slide, followed by the optic (if present). Naturally, the standard open sights will need to be removed as well. We had never installed sights on our Rival Arms Faction slide, but if you have sights in place, use a GLOCK front sight tool to remove the front sight retaining screw. The rear sight must be pushed out of the dovetail (toward the right side of the slide) with a sight pusher. For that, we use TRUGLO’s Sight Installation Kit. This kit includes easy-to-follow directions for setup and use.

The Rival Arms rear tritium sight includes a set screw to help maintain position in the slide dovetail. Remove this prior to installation onto the slide.

Slide the new rear sight into the dovetail, pushing from right to left. The sight should be able to insert 1/3 to 1/2 of the way into the dovetail by hand. If not, use a flat file and CAREFULLY remove just enough material from the base of the sight until it will move into the dovetail by hand 1/3 to 1/2 of the way.

Follow the instructions for the sight installation tool you are using. The sight pusher will move the sight from the right to the left in the dovetail. The objective is to center the sight in the slide, with equal distance left and right.

We find it easiest, due to the high torque often required to push a sight into a dovetail, to secure the installation tool to a bench-mounted vice. When you feel you have reached or almost have reached center alignment, stop and check your work. You do not want to overshoot the centering of the sight as moving it back to the right could compromise the interference fit between the sight and the dovetail.

Once you have reached or nearly reached the center position, remove the slide from the installation tool and carefully measure the side of the sight with both sides of the slide. The ideal location will measure equally on both sides. Continue to adjust until you have reached the center position. Once in position, clean the threads of the set screw with denatured alcohol and apply a small amount of blue Locktite to the threads and secure the set screw in the rear sight.

Moving to the front sight installation, use denatured alcohol to clean the front sight screw threads.

Install the front sight into the slide, making sure the tritium vial is facing the rear of the slide.

Apply a small amount of blue Locktite to the front sight threads.

Screw the thread into the bottom of the sight. TRUGLO’s GLOCK Front Sight Tool works well for this installation.

As you can see, the Rival Arms M.O.S. sight is perfectly sized to work without interfering with an installed optic.

The sights are tall enough to provide a clear sight picture when used with or without an installed optic. Now we have a slide assembly that will provide reliable aiming solutions under any condition.

Shoot On Editor-in-Chief Rob Reaser is a lifelong outdoorsman, former magazine editor, columnist, and contributing editor to numerous national publications in the automotive and outdoor segments. He has also authored and co-authored several DIY gun building books. His shooting and hunting passions cover everything from traditional archery and big-game bowhunting to the latest in handguns, rifles, and reloading. Rob has a troublesome habit of pulling guns and things apart to see how they work; occasionally, he manages to get them back together...

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