First Gear | Our First SHOT Secret: Glock 17/19 MOS

posted on January 18, 2016

Glock G17 and G19 MOS

Secrets are tough to keep around SHOT Show time, and we’re glad the expiration date is up on this one: Today, the Glock 17 and Glock 19 join the list of pistols offered in the MOS—Modular Optic System—configuration. 

Not that we can blame the folks in Smyrna: If nothing else, it’s fun to have something new, or at least newish, to spring on industry friends and competitors alike. And we hope nobody is silly enough to think the folks at Glock didn’t know that their pseudo-secret was out, or at least deduced by many. Still, the forms must be observed.

But from our perspective, it stunk not to be able to talk about the G17 and G19. No mystery as to why: They’re splendid steps forward, and no less so if presaged by the MOS G34, G35, G40 and G41 models. But from our perspective, it stunk not to be able to talk about the G17 and G19. No mystery as to why: They’re splendid steps forward.

A quick primer: Out of the box, MOS pistols run just like their similarly numbered non-MOS counterparts. Reliable, accurate, reliable, easy to care for, durable and reliable, they’re soft-shooting icons of the striker-fired genre. They depart from their forebears, however, in the form of a removable plate on the top of the slide, aft of the ejection port and forward of the rear sight. A little zip-zip with a T10 Torx, and one of four (provided) plates stands ready to accept a red-dot/reflex sight from any of these manufacturers. All MOS pistols sport the Gen4 adds too: Dual spring recoil assembly, sizing/beavertail backstraps, enlarged and left/right swappable magazine release, and RTF grip-enhanced frames. 

We think it’s the no-brainer of 2016 SHOT that these Glock mainstays will garner even more appeal with their reflex-ready status. Granted, reflex sights aren’t exactly new on Glocks, but the simplicity of the factory method is dandy—no more sending your slide off for an unknown term, and getting back a configuration that only matches one type or manufacturer’s sight. 

Then there’s the shooting part. We admit to a shortcut here: We simply popped our Burris FastFire III off our review G34 and onto the G17 (and, a little later, the G19). A couple of interesting things emerged.

First, we saw none of the tendency—common in earlier methods of adding reflex sights—to make the pistols finicky relative to bullet weight (by introducing mass-related changes in slide dynamics.) Everything from 90 to 158 grain ran well and accurately. Second, and very much in line with our MOS G34 experiences, accommodation to the reflex setup was surprisingly rapid, even on the draw stroke. (When transitioning to a reflex sight, it’s especially advantageous to remember to bring the gun up to the eyes/sight line, and not the head and eyes down to the gun.) 

Lastly—and a long-appreciated benefit of reflex sights on any firearm—is the ability to shoot rapidly, with both eyes open, and with both target and aiming point in focus. Doing so is an absolute pleasure.   

Two of Glock’s most popular pistols now put this rugged, reliable technology at your fingertips as never before. 

Visit Glock at


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