MOS1

GLOCK released their MOS, or Modular Optic System, line of pistols a year ago. With the ability to mount a variety of reflex-style red dot optics to the slide, the GEN4 MOS offerings kicked off with big guns suitable for hunting and competition: the G40, G41, G34, and G35. Building on that success and much to the surprise of, well, nobody, GLOCK has given the MOS touch to two of their most popular pistols, the G19 and the G17. I promised Gaston’s gang that I could keep a secret and got my hands on these guys in early December, immediately turning the G19 into my EDC. . .

MOSholsters

As the G19 and G17 are two of the most popular pistol models in the world and are used as a basis for comparison in just about every polymer-framed and/or striker-fired handgun review, plus are already reviewed on TTAG here and here and here, I’m not going to re-review them. These are GEN4 GLOCKs, and they’re functionally identical in every last way to the typical GEN4 G19 and G17, other than the MOS components. It’s a GLOCK. You know exactly what you’re getting. These two have proven to be no exception. MOS, then. . .

MOS6

Each MOS comes with four mounting plates to fit the most popular reflex sights. I have a 4MOA dot JPoint, which is a great little sight, but apparently isn’t popular enough to warrant an MOS plate of its own or a listing in any compatibility guide. Good news, though, as it fits perfectly on plate #04, which is billed as being for the Leupold DeltaPoint. However, you’ll need to pick up a pair of M4x0.7 or M5x0.7 metric bolts.

MOS3

From the factory, a blanking plate is installed on the MOS pistols.

MOS2

It fits nicely and makes the guns look like their non-MOS compatriots. The first step to mounting an optic is to remove that blanking plate.

MOS7

Once you’ve chosen the correct mounting plate for your optic, use two of the provided bolts to attach it to the slide. GLOCK has already applied the thread locker.

MOS8

Mount the optic to the plate, and you’re in business.

MOS4

The mounting plates are serrated to match up with and effectively extend the slide serrations. I haven’t been shy about using the optic for racking the slide, though. It obviously works extremely well for that purpose — lots of purchase — and so far it doesn’t seem to mind.

MOS5

GLOCK’s complaint folder is overflowing with gripes about the MOS guns’ factory sights. And by factory, I mean the exact same polymer sights that come on the non-MOS versions. They’re too short to co-witness with any of the reflex sights that fit the MOS mounting plates. Well, other than my slim little JPoint…

MOSdot

It’s just low enough to allow almost full alignment of the factory sights without losing view of the front one. Actually, it would be better without the factory rear sight in place, as the JPoint has a rear sight notch molded into it that happens to work pretty dang well with the factory GLOCK front. Plus I tend to prefer an all-black rear sight anyway.

Since co-witness heights will be different with just about every optic out there — all of them (as far as I know) are taller than the JPoint — it makes sense to me that the MOS guns just come with the standard, cheap sights. I’d guess that most MOS owners would replace them no matter what, and taller sights would risk the chance of actually blocking the dot on some optics. At any rate, if co-witnessing is on your checklist then you’ll definitely be exploring the near-limitless GLOCK sight aftermarket.

MOSholsters2

As mentioned, the G19 MOS has been my everyday carry since early December. It’s likely to remain in that role until summer, when I may or may not switch back to a slim little 9mm single stack job. I picked up a mess of kydex to try out, and so far so great. The Cook’s Holsters IWB with adjustable clip holster (reviewed here) works just as well for the G19 as it does for my other EDCs, and with the larger size of the GLOCK I decided to dive into the deep end of appendix carry with the help of the guys at T.REX ARMS. Their Raptor is imminently concealable, and the Sidecar adds a backup mag to the mix. I also picked up a Fenrir OWB that fits both the G17 and G19. Reviews after I break ’em in further.

MOSholster3

While the JPoint’s auto brightness adjustment dims it to near-off when it’s in the dark of IWB concealment, helping the 2032 battery last a few months, any electronic sight can die at the wrong time or break for various reasons. This is why backup sights are so important on a defensive-use firearm and why, in a case like this one, they need to be tall enough to be visible through the lens of the optic.

Well, at least if you want to hit targets at longer ranges. A lot of people are actually slower with a red dot on a pistol than with irons, and Nick reminded me that it’s because they’re waiting to find and center the dot. At typical self-defense ranges, forget the dot and just use the reflex sight’s frame like a ghost ring — if it’s visible inside the screen, you’re on target and well within minute of bad guy. For this sort of use, the ability to align the iron sights doesn’t matter. Live battery or dead, dot or no dot, broken lens, etc, you still have a self-defense sight picture.

But getting back to stretching out the range, if that dot is down then the irons absolutely come into play. That would be a shame, though, as a nice red dot is awesome for accurate shooting with a pistol. Especially with the sights on most self-defense pistols, which are designed for quick acquisition and rough alignment rather than high precision. At 3, 7, or 15 or so yards this is ideal, but move back to 50 yards and the confidence level and speed drop. The 4 MOA dot on this JPoint is fine enough for head shots on torso silhouettes out to 100 yards, even if reliably making those shots is a tough ask. Torso hits, though, are available on tap.

Conclusion

The G19 and G17 MOS pistols are the same GLOCKs we’ve come to know and trust. They do, however, open up a world of optics possibilities that don’t easily exist with the standard models. The addition of a red dot can be a big plus for competition, hunting, self-defense, teaching new shooters, and more. Red dots are as simple as it gets for sight alignment, and the right dot can provide bullseye-hitting confidence out to significantly longer ranges than most of us would attempt with standard pistol sights. These little reflex optics are surprisingly unobtrusive for CCW use, and I expect we’ll continue to see more and more optics-ready pistols from GLOCK and most other manufacturers hitting the market in the future.

Specifications (GLOCK G19 GEN4 MOS and G17 GEN4 MOS)

MSRP: $726 (both models)
Everything Else: Identical to standard G19 GEN4 and G17 GEN4

Ratings (out of five stars)

Accuracy: * * * * *
Compared to the non-MOS versions, the ability to slap a red dot on it ups the accuracy potential. Not the gun’s, per se, but definitely the shooter’s.

Customization: * * * * *
Any GLOCK is going to get five stars here, as the aftermarket support is the strongest in the pistol world. Add the ability to easily mount optics, and the MOS versions are really at five stars-plus.

Overall Rating: * * * *
To preempt freakouts, please remember that the overall rating is not the cumulative total of the ratings above it but, rather, takes into account all aspects of the gun, explicitly rated and otherwise. I’m not the biggest GLOCK fan in the world. I’d likely rank any of them at three stars, and feel free to input * * * for all of the missing categories above. After all, GLOCKs are the standard. But then I’d give ’em a well-deserved fourth star for stellar reliability and durability. Optic or not, the MOS guns still have standard GLOCK triggers, plastic GLOCK sights, GLOCK ergos (GEN4 did improve on that a bit), and BLOCK looks. So four stars it is for a pair of very good guns, one of which is my new EDC.

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33 Responses to Gun Review: GLOCK G19 GEN4 MOS & G17 GEN4 MOS

  1. I’ve found that up close, only a few yards, getting your front sight on target is faster than doing so with the dot. But once you get to medium and long range (for a pistol), or you or the target are moving, the dot is way faster. I’ve been shooting my ATEI G19 with rmr for a while now.

    • Yeah but as mentioned in the review, I wouldn’t even suggest looking for the dot at close range. Just use the frame of the reflex sight as a sort of picture window. At self defense ranges that’s more than accurate enough, and once you get into normal shooting position that dot is going to center itself. Also, when I’m drawing the pistol and raising it up before firing, I’m still tracking the front sight as usual and as that front is coming down and my arms are going out and the sights are getting close to alignment, the dot appears. It’s very easy to try and track the frame of the optic instead and wait for the dot, but tracking the front sight as usual will get you into normal alignment even faster. Close range, though, focus on target with both eyes and “ghost ring” with the optic’s frame.

  2. I replaced a RMR for the JPoint on my G40 for the reasons mentioned. I ran 250 rounds through the G40 last week in 1.5 hours. No issues and so easy to use the JPoint from 5 to 25 yards.

  3. I hope the Glock shop will offer this as a retrofit. I want to put an optic on my G20, and i like the look of this system. …and I’d rather pay Glock than Lone Wolf.

    • Yeah when I read the price I said “ouch” very firmly in my brain.

      This is probably not an upgrade I’ll ever be doing. Maybe when my eyes start to go? I feel like I’d just do a laser guide rod at that point, though.

    • Meh, at a bare minimum you are going to pay a competent gunsmith a minimum of $125 to mill the slide for a red dot. If you want them to retain a rear sight dovetail thats going to be ~$25-50 more. If you ever plan to run the gun without the optic mounted you are going to pay them another $25 or so to cut you a block off plate so you don’t have a gaping notch in the slide. You may decide you don’t want bare metal exposed on the slide under the cutout so you may get the slide refinished which could be anywhere from $50 on up to 3x or 4x that much depending on what option you choose.

  4. Quick question about the rear sight on this. Does it appear to be compatible with standard rear sights available for the non-MOS Glock 19? Comparing Google searches for the two leads me to believe the rear sight on the non-MOS G19 is about 1/8-1/4″ further up the slide. Is that about right? If so is there still enough room to mount say a Trijicon suppressor sight (its not perfectly centered and slightly reflexes to the rear of the dovetail) on the rear without it hanging off the back of the gun?

    I have been shopping for an RDS compatible 9mm ever since I spent nearly 11 hours trapped in a car with Tyler listening to him rant and rave about his RDS equipped M&P on the way out to and back from Pecos (also somewhere in the middle I got to watch helplessly as he wiped the floor with me and pretty much the rest of the field in the pistol shooting stages with the aforementioned M&P).

    So in my quest I got a chance to play with an M&P Pro CORE recently, and liked it for the most part, but the biggest bummer was that the suppressor sights S&W installed look and feel a little cheap, and more importantly they are just plain white three dot sights, no night sights like an FNX Tactical or similar. To my knowledge nobody makes extended height night sights for the CORE series or any M&P for that matter. I think Ameriglo makes an extended front sight post, but nobody makes an extended rear sight for the CORE or standard M&P. Which is irrelevant because the dovetail on the CORE doesn’t match the non-CORE M&P or anything else on the market since most people who put an RDS on their M&P mill out the old dovetail to mount the sight and have a Glock dovetail cut in front of the optic to provide a better co-witness with the RDS. Even if the CORE did have the standard M&P rear dovetail the sights would hang off the back of the slide by 1/4-1/2 inch. Hopefully Glock has not been so shortsighted (get it? haha).

    I like these special versions, but it is moderately annoying when you lose compatibility with regular aftermarket accessories. Because as cool as these are, there isn’t a huge incentive to make something for only a small percentage of the market. Hopefully these things become way more mainstream to force the aftermarket off its collective ass, because if you are going to mixing and matching parts you might as well just go with something custom.

    • A comparo of the pictures here and my G19 confirm that the dovetail on the MOS is further back than the non-MOS version, my Ameriglo sights would certainly hang off the back of an MOS slide.

    • CZ Custom sells one. I’ll have SHOT Show photos and a video booth tour with Angus Hobdell up in the next day or two. (it’s a fully pimped-out P-09, so it’s more $$$ than these Glocks)

  5. It’s like 150 more retail for an mos than a regular new gen 4 glock, after a while and the novelty wears off it will probably be a 100 difference. Sure u can spend 350 on a line wolf mos slide but why? Spend the extra get a glock mos and u have 2 guns and way better resale value….

    • I think the main benefit of the Glock MOS system is that it’s compatible with most of the reflex optics on the market. The aftermarket slides are milled for one specific optic and there’s no way to modify that later. Of course, on the flip side when it’s milled for a specific optic it gets bolted directly to the slide, whereas with the Glock there’s an adapter plate between slide and optic.

      It is a pretty large price jump vs. the non-MOS Glock, but considering how much additional machining is required plus the fact that it comes with a kit of 4 adapter plates, the blanking plate, and extra hardware, the cost makes perfect sense as it clearly costs Glock more to manufacture these.

  6. How long do the batteries last in the red dot? If I carry for a few hours a day what can expect regarding reliability of the sight and battery life?

    • Oh like a year or more if the gun is mostly in the dark. The sight is always on, but if it’s in the dark then the dot is really, really dim. It automatically gets brighter based on ambient lighting. My G19 is either in a bedside safe or concealed on my person, so it’s in the dark 99.5% of the time. This battery was installed in November and it’s going 100% still. I’ll probably swap it out in May for a new one, though. Thinking I’ll do that every 6 months. I have a 20-pack of Sony lithium CR2032s that ran me $8.00 so they aren’t exactly expensive batteries. I’d probably swap them more often if the sight didn’t have to be removed from the gun to do it. However, I’ve already taken it off and put it back on two times and confirmed that zero was not affected.

  7. What length were the machine screws used to mount the jpoint to the plate? want to make sure I have them on hand when the optic shows up.

  8. I just ordered a Glock 19 MOS and a JPoint red dot. You said ” However, you’ll need to pick up a pair of M4x0.7 or M5x0.7 metric bolts.”
    What length did you purchase and where did you get it?? What type of head?

    Than you very much.
    Dennis
    P.S. Excellent write up and info !!!

    • I asked the same question above, for my Mos and jpoint. We’re you able to tinker yet and find out?

      • For my mos and jpoint, I ordered these on ebay, and they worked fine with blue Loctite:

        M4 – 0.70 x 6mm – Qty 10 – LOW HEAD SOCKET CAP Screws – DIN 7984 Blk Alloy 10.9

  9. I’ve had Glocks now for over 20 years. Many different Gens and calibers. I’ve been carrying a Gen 4 Glock 26 with Trijicon HD sights (orange front sight, and Pearce +3 mag extensions). and have a few other Glocks currently. I started off about a year ago with an FNX 45 Tactical with Trijicon RMR as my first red dot. I had a gun store mount and adjust the sight for me, then followed by a S&W M&P CORE 9mm with the same set up. These guns are so easy to co witness the red dot. Last weekend I got the G19 MOS at a gun show for $569 plus tax, and was so happy. I wound up coming home and having my local gunsmith mount Trijicon Tough and Bright suppressor height night sights, and mounting the RMR from the S&W on it. I then bought a Vortex Venom for the S&W (since that’s just a target/range gun). The issue I had was the plate kit didn’t come with the correct size screws to mount the RMR and when I went to the range yesterday to dial in the red dot, as I was shooting what I thought was the correct size screws, one actually fell out, and the other once came loose. I even used lock tight. I got home to find several different sized screws from my original install on the S&W, and found some that work till I can get the actual size needed. Anyway. Once I get the dot dialed in correctly (which for some reason on this gun is a pain in the ass compared to my two other pistols) I will use this for my EDC. It already fits in several of my IWB and OWB kydex holsters. I use a MTac Minatour holster for most of my IWB carries, and a custom kydex for OWB that allows me to carry with my Streamlight TLR 1 HL (630 lumen) light. I do sometimes carry one of my compact HK’s or Sigs as well, but this new G19 MOS might just be my favorite carry pistol.

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