Glock Modular Optic System (MOS)

Though so many Glock fans were looking for the announcement of the Glock single-stack compact 9mm pistol, Glock did not feed that hunger at SHOT Show this year. I’m beginning to think that Glock won’t produce what the market demands, simply so they can maintain some kind of twisted belief that they are in charge of the market. Instead they promoted their new Modular Optic System (MOS) pistols.

There has been an ever-increasing movement in many of the competitive shooting circles to have a pistol with a red dot reflex sight. The benefits of reflex sights on a pistol are perhaps even greater than reflex sights on a long gun. The reflex sights allows the shooter a much quicker target acquisition by removing the need to align multiple, often difficult to see, small sights during high stress shooting situations.

Glock engineers responded to this movement with the MOS series of pistols. With handgun shooting distances typically being in such close quarters, bore-to-sight off-set issues can have dramatic effects on shooting accuracy. If they simply added a mounting rail or other system on top of their standard Glock handguns they would only exacerbate the problem. In other words, having a red dot sight so far above the bore on a handgun really messes with the whole point of red dot optics – point and shoot. To overcome that problem, Glock engineers dug into the slide itself to provide as low of a sight setting as possible.

Unlike some firms that cut slides all the way through to attach mounting brackets, Glock engineers cut into the slide just enough to allow interchangeable mounting plates to be installed. Enough of the original slide metal remains to sustain structural integrity and prevent moisture or debris from entering the trigger group. The result is a fitting that is very secure.

The cut in the slide is shallow enough that is does not expose the firing pin group. Not all the options on the market can make that claim. The front of the cut does get very close to the extractor but, the Glock guys said engineers were confident the slide would hold up under heavy use. The strength of the metal used in the slide, and the Glock Melonite-type finish (no longer Tenifer due to US EPA regulations on hazardous by-products) have been selling points by Glock from their beginning. Unfortunately, even with the cut into the slide, and the relatively slim profile of pistol red dot optics, the standard Glock sights will not co-witness with the red dot optic like many rifles can.

A great feature of the Glock MOS pistols is that the sight mounting plate does not remove the rear sight. If for some reason the shooter wants to remove the reflex sight, they can put in the base cover plate to enclose the slide, and still have full use of front and rear fixed sights.

Glock MOS handguns come with (5) interchangeable mounting plates:

Plate 00 – This is the base cover for when no red dot optic is mounted
Plate 01 – Fits EOTech, Docter, Insight, and Meopta optics
Plate 02 – Fits Trijicon RMR
Plate 03 – Fits C-More
Plate 04 – Fits Leupold Deltapoint

The versatility of the MOS system is a great design feature that allows shooters to update or modify their red dot optic selections if desired. Simple mounting tools are all that are needed for adjustments or changes, and the sights can be switched out in just a few minutes. Glock provides a brochure explaining the mounting process and proper Plate selection with each MOS handgun. At the Industry Day at the Range during SHOT Show, Glock had MOS pistols with Leupold Deltapoint and Trijicon RMR optics.

I was able to shoot a .40 S&W and .45 ACP version of the Glock MOS at the range. Shooting the Glock MOS handguns was a nice transition from the Trijicon 3-dot sights I’m accustomed to normally. Acquisition of targets was very quick, as to be expected, and finding the dot after recoil was nearly seamless with proper grip and recoil management. Accuracy at 15-yards was impressive, with follow-up shots being accurate as well as fast.

Glock representatives explained that their system will provide as much stability as possible for the red dot optic to do its job. Earlier versions of pistol mounted reflex sights suffered from jarring during recoil, sometimes causing them to turn off, or quickly lose their zero. Glock representatives reported that red dot optics advancements are providing a much better maintenance of zero and long-term durability.

Currently the Glock MOS is only available in the following long-slide models:

G34 – 9mm
G35 – .40 S&W
G40 – 10mm
G41 – .45 ACP

MSRP – $699.00.

I asked if there would be the option to simply purchase an MOS slide with mounting plates so a shooter could switch out with their existing Glock handgun. Unfortunately, Glock is Glock, and the answer is NO! To have the Glock MOS you must purchase an entirely new handgun. The explanation is because Glock stamps both the slide and the receiver with a serial number so they are not going to send a different serialized number item to an existing frame. I’d like to think that Glock would change their mind if the MOS takes off in popularity but, like many, I’ve held my breath for Glock before, and I’m not too interested in passing out.

There are already several Level I holsters on the market that will accept the Glock MOS handguns. Talking to the Glock reps and some reps from Safariland, there will be Level II holsters ready for the Glock MOS to satisfy law enforcement or government users needsLevel III holsters are still a bit down the road, but will likely be developed as demand grows.