GLOCK G40 Gen4 MOS Semi-Auto Pistol




Reliability and simplicity of use have made GLOCK® pistols a favored sidearm all over the world. The GLOCK G40 Gen4 MOS Semi-Auto Pistol is designed as a serious hunting, tactical, or competition handgun. The G40 shoots the powerful 10mm cartridge, capable of downing deer, hogs, and bear. The long slide reduces muzzle flip considerably to keep the user on target during rapid fire, and also increases sight radius. The G40 Gen4 MOS comes from the factory with a Modular Optic System milled into the top of the slide for mounting aftermarket reflex and red dot sights. The MOS slide comes with a removable cover plate that fills the milled out area, and 4 brand-specific adapter plates and a hex wrench. The pistol also has a white dot front sight, and an adjustable white outline rear sight. A modular back strap allows shooters to instantly customize the grip to an individual shooter’s hand size, or to cold weather gloves. The polymer frame utilizes GLOCK’s Rough Texture to provide a sure hold on the pistol in adverse conditions, and the enlarged magazine catch is reversible, accommodating left or right-handed shooters. An integral accessory rail in front of the trigger guard allows for the attachment of a plethora of aftermarket tactical flashlights or laser sights. The GLOCK G40 Gen4 MOS Semi-Auto Pistol is an ultra-reliable, accurate and extremely controllable handgun, making it an ideal choice for outdoorsmen and competitors alike. Ships with three 15-round magazines.

Manufacturer model #: PG4030103MOS.

Designed as a serious hunting, and tactical handgun
Shoots the powerful 10mm cartridge
Long slide reduces muzzle flip
MOS (Modular Optic System)
Ready to mount reflex sights
Adjustable white outline rear sight
White dot front sight
Modular back strap
Rough Texture grip frame
Integral accessory rail
3 high-cap mags
Review: Glock G40 Gen4 MOS Pistol

GLOCK has been striving to fill its customers’ requests for semi-autos with longer barrels and slides since the introduction of the 6.02” barrel 9 mm G17L in 1988. The benefits of an extended slide assembly include a longer sight radius for a more precise sight picture, more rifling to stabilize the bullet, longer burn times for the powder which in turn can increase bullet velocity, and a bit more weight at the muzzle end of the barrel to help manage felt recoil.

In 1994, the next Glock long slide arrived in the form of the .40 S&W G24. Both the G24 and G17L were either dropped from the Glock catalog or relegated to limited production with the arrival of the “Practical Tactical” G34 (9 mm) and G35 (.40 S&W) in 1998. These competition models have slightly shorter 5.31″ barrels, cut outs in the tops of the slides to accommodate ported barrels and they are currently available in both Gen3 and Gen4 Configurations. 2014 heralded the arrival of the first Practical Tactical chambered in.45 ACP, the G41. GLOCK G40 Gen4 MOS Pistol

Now, at last, Glock has come around to taking care of its handgun hunting fans with the release of the long-slide Gen4 G40 chambered in 10 mm, which has been lovingly dubbed Glockzilla by some enthusiasts. It’s no coincidence that this model arrived the same year that the company launched the factory installed MOS (Modular Optics System) for mounting reflex and red dot sights. The MOS feature is currently available on four Glock models including the G34, G35, G41 and the G40. I had my first opportunity to shoot the G40 at the 2015 SHOT Show, so I was looking forward to shooting it again for this review.

When designing the G40 10 mm, Glock engineers followed the same design ideas used for the G41 .45 ACP. The polymer frame, recoil assembly, controls and 15-round magazines are lifted directly from the Gen4 G20 10 mm. The Gen4 features include the Rough Texture grip frame, 2″ accessory rail for lights and lasers, removable back straps and an enlarged reversible magazine release button. The polymer sights, consisting of a white dot front and windage-adjustable white outline rear, are a common factory option. GLOCK G40 Gen4 MOS Pistol

However, instead of just elongating the G20’s heavy-duty slide to accommodate a longer barrel (making the pistol unnecessarily weighty), a slim, thinner-walled slide with external dimensions comparable to the Practical Tactical models was installed. Even though the G40 does not have a cut out in the top of the slide, the pistol still weights 2.5 ounces less than the Standard size G21. The result is a 10 mm pistol with a much better balance in hand than one might expect from a long slide.

The G40 ships with the MOS Adapter Set 02, which is a package of parts containing four numbered optics base plates, screws and a small wrench. The pistol’s slide is milled, drilled and tapped to accept a removable plate located between the chamber and rear sight. This plate is contoured to match the shape of the slide when an optic is not in use.
Installing an optic using the MOS components is a simple process. Start by removing the magazine, locking the slide in the open position and verifying the pistol is completely unloaded. If you have a gunsmith’s pistol stand, you are ready to get started. If not, it will be easier to install the optic if you field strip the pistol so that the slide can rest directly on a flat work surface. Remove the contoured slide plate from the slide by loosening the two slightly longer retention screws using the provided wrench. Then select the correct optics base plate by pairing the plates with the optic until you find the right fit. Attach the base plate to the slide using the shorter screws provided in the MOS package. The slide is now ready for the installation of the optic.

For this test, I opted to use the top notch Triiicon RMR 1.0 MOE Red Dot sight (RM09-700304) which arrived from the factory affixed to a clamping base designed to fit Picatinny rails. In order to mount the RMR using the Glock MOS system, it was necessary to order the Trijicon AC32064 RMR Mounting Kit so as to have the correct set of mounting hardware. So when selecting your optic, make sure to communicate with your product provider to ensure you have all the right bits and pieces. GLOCK G40 Gen4 MOS Pistol

The G40 arrives with a substantial set of accessories in addition to the MOS adapter set. Along with three 15-round magazines, a magazine loader and a tiny sight adjustment tool, there’s a set of four removable back straps with a retention pin and a punch. The purpose of these back straps is to help the operator adjust the grip shape and trigger reach to fit their hands. Two of the straps maintain the standard grip shape but increase the trigger reach by 2 or 4 mm respectively. The other two back straps also change the trigger reach by 2 or 4mm with the addition of an extended beaver tail to help protect the shooting hand from slide bite.

At the shooting range, the G40 demonstrated Glock’s usual level of reliability. I fed, fired and properly ejected every round of ammunition with no malfunctions during informal or formal testing. All of the controls worked properly with the slide locking open on the last shot and magazines dropping free from the grip when the magazine release was pressed. The trigger exhibited the typical love-it-or-leave-it Glock qualities with a slightly mushy take up and a distinctive click when the trigger reset. GLOCK G40 Gen4 MOS Pistol

I brought along the little wrenches provided with the MOS system and Trijicon RMR just in case any screws shook loose in the course of fire but none of them did. The RMR reflex optic was easy to sight in and provided for quick target acquisition. It doesn’t take long to appreciate why this sight system has become so popular for sporting and defensive applications.

As expected, the felt recoil produced by the pistol when firing a variety of 10 mm ammunition ranged from brisk to stout. However, the recoil was not painful or punishing even with the hottest loads. The elongated slide and other ergonomic features made the pistol controllable, and thus enjoyable, to shoot. Even though the 10 mm cartridge is not as popular as some semi-auto calibers, there is a good selection of practice, defense and hunting grade ammunition available from several different manufacturers these days. GLOCK G40 Gen4 MOS Pistol

While checking the pistol’s accuracy with bench rested 25-yard 5-shot groups, bullet velocity was measured by firing 10-shot groups next to a LabRadar chronograph to see how the 6.02″ barrel affected ammunition performance. Surprisingly, the extra barrel length did not produce as much of a velocity boost as I would have expected.

Armscor International produces a moderate recoil practice load topped with 180-gr. full-metal jacket bullets which has performed reliably for me in several guns. The average velocity when fired from the G40 was 1148 fps., which is statistically the same as the company’s listed velocity of 1150 fps. This round produced a best single 5-shot group of 3.09″ with an average of 3.29″.

The most accurate load was the Double Tap 125-gr. Tac-XP jacketed hollow point with a best single group of 2.74” and an average of 2.89″. Flying along at a respectable list velocity of 1600 fps., this round also exhibited the greatest velocity increase of the test set with an average of 1685 fps. Federal Premium’s 180-gr. Trophy Bonded jacketed soft points turned in a best group of 2.75″ and an average of 3.01″. Velocity only increased a little, from a list speed of 1275 fps. to an average of 1289 fps. GLOCK G40 Gen4 MOS Pistol

The Glock G40 Gen4 is a pistol I’ve been waiting to see for some time. When the G41 .45 ACP was released I had my fingers crossed that there would be enough customer demand for Glock to produce a similar long slide configuration in 10 mm. The Gen4 frames fit my hands more comfortably than the Gen3 models and the addition of the MOS feature is certainly a plus. The timing of the G40’s arrival couldn’t be better. Finally, we can enjoy a reasonably priced 10mm long slide with the rugged reliability of a Glock without the need for expensive aftermarket parts or gunsmithing.

Manufacturer: Glock;
Model: Glock 40 Gen4 MOS
Action: Safe Action
Caliber: 10 mm
Finish: Gas Nitrate Slide, Polymer Frame
Grips: Rough Texture, Multiple Back Strap System
Sights: White Dot Front, Adjustable Outline Rear
Barrel Length: 6.02″
Overall Length: 9.49″
Sight Radius: 8.19″
Trigger Pull: Listed 5-lbs. 8-oz., Tested 5-lbs. 4-oz.
Trigger Travel: ~0.49″
Height: 5.47″
Slide Width: 1.13″Inches
Frame Width: 1.28″
Accessory Rail: 2″
Weight: 28.15 oz. (Unloaded)
Capacity: 15+1 Rounds
Twist: 1:9.84” RH
Rifle Grooves: Hexagonal
Accessories: Hard Case, 3 Magazines, Magazine Loader, MOS Adapter Set 02, 4 Removable Back Straps, Back Strap Tool, Rear Sight Adjustment Tool, Cleaning Brush, Lock, Owner’s Manual

Gun Review: GLOCK 40 MOS

I finally got my hands on the much heralded GLOCK G40 MOS, the six-inch, optics-ready 10mm juggernaught. I shot its older, littler brother the G20 as my first entry in my truck pistol series – and found it wanting. As I said in that post, I want to love GLOCK pistols. I generally find them just okay for the job. I keep trying GLOCKs in the hopes that I may one day find one I can shoot well. I may have found it . . .

GLOCK’s website lauds the G40 MOS as “the ultimate choice in semi-automatic gaming pistol.” When RF handed me case I looked at the box and thought, “Well, they sure aren’t wasting money on packaging.” Gaston’s mob stuffs the 28 oz. long slide powerhouse into the same cheap, bursting-at-the-seams plastic case they use for all their handguns. Opening it revealed a jumbled mass of backstraps, mounts and screws, arranged with all the organization and presentation excellence my three-year-old would muster. GLOCK G40 Gen4 MOS Pistol

The firearms farrago included a pack of base plates. Like the FNX-45 Tactical, the G40 MOS (Modular Optic System) model lets owners mount a range of pistol optics (think pistol red dot sights like a Trijicon RMR, Leupold Delta Point, Meopta MeoRed, etc.) on the slide with no more trouble than tightening a few screws. So I added Triiicon’s ever popular RMR, a combination featured in GLOCK’s product literature. Unlike the FNX-45 Tactical’s or the S&W CORE series, the G40 MOS’ factory front and rear sights weren’t raised. They didn’t co-witness the RMR’s dot with the stock sights. Close, but not quite perfection.

RMR on MOS, I was ready to shoot. One problem: the three magazines supplied were conspicuously empty, and proved to be surprisingly difficult to fill. In a tragic reversal from my STI Nitro 10 review, I had plenty of magazines and no ammo. Cheap 10mm ammo wasn’t to be found, so I shelled out the cash for 200 rounds of the better to very good stuff. My supply included HPR, two different Hornady loads, and some DoubleTap ammo. Lesson learned, again, for the third time: if I choose a 10mm for my perfect truck pistol, I’m reloading my own. GLOCK G40 Gen4 MOS Pistol

To the range!

The only GLOCKs that fit my hands well are the full-frame models, and this one was no different. The gun still doesn’t point naturally for me, but man, the G40 MOS’ grip feels good. One-handed, I get a strong grip all the way around the gun. The raised dots, the material itself and the finger grooves gave me a solid lock on the frame. This and a good rest made zeroing the RMR a breeze; I got ‘er done in six rounds.

Because the gun felt so good in my hand, I put a few magazines down range one-handed. At 15 yards, right or left handed, this G40 MOS is the best shooting of the higher powered pistols I’ve ever shot. Shooting right handed, one shot per second at 15 yards on a 5 ½” plate? Easy. And that’s with a 10mm handgun. I don’t shoot this well one-handed with my Wilson Combat WC92FS in 9mm.

Backing up to 25 yards, the problem I suspected would occur when I zeroed the gun revealed itself in full force. The dot was too big to be accurate. Fast, yes. Accurate, no. The dot size on the RMR obliterated the 5½-inch target at the 25 yard line. As this was the minimum distance I’d be shooting at, I reluctantly removed the RMR – and was instantly rewarded for doing so. GLOCK G40 Gen4 MOS Pistol

GLOCK haters of the world note the 2” groups at 25 yards I shot with the G40 MOS resting against a makeshift bean bag on a stump. From the kneel, I was shooting regular 3- to 3.5″ groups with anything I fed it. Don’t get me wrong. The 10mm GLOCK still didn’t point naturally. If I was to shoot and just guess at the accuracy of the round, I would have said 5”. I was fighting the gun, and I felt like it was all over the place. But it wasn’t. Those little paper holes don’t lie.

AT 25 yards, the most accurate round, for once, was not the Double Tap. That 200gr FMJ Flat Point round shot a 2¼” group, plenty good for any game in the Texas Hill country out to 50 yards, maybe more. The Hornady 180gr XTP round shot a 2½” group and Hornady 175gr Critical Duty round scored a 2¾” group. The best of the bunch: a 2″ group using HPR’s 180gr JHP. Of all of those, I’d stick with the Double Tap flat point round for hunting, purely for penetration. But as none of these groups were shot from a bench, any of those rounds are good enough for hunting. GLOCK G40 Gen4 MOS Pistol

Ever wonder why Pennsylvania long rifles had such long barrels? It’s a lot easier to aim precisely when you have more than three feet of distance between your sights. The same principle applies here. That G40 MOS’ 6-inch barrel buys you a lot of real estate between the sights. In fact, the G40 MOS has a full 8.9″ overall length – more than two inches longer than the G20. That’s a lot of sight radius. Plus, all that weight up front soaks up recoil in an otherwise not-so-heavy gun.

Good Lord I’m going to get some hate for this, but the G40’s trigger ain’t that bad at all. Their website says that it’s a 5.5 lb trigger pull weight. It’s every bit of that but it’s a smooth pull with very little grit and none of the stacking or squishyness I’ve come to expect from GLOCKs. The reset is one of the best I’ve ever fired in any semi-auto pistol, including many 1911s. Short, crisp, very solid and right there. I’m sure that went a long way to the ease of the one-handed shooting I noted before. Whoever at GLOCK worked on the reset, please call FN and show them how to do it.

At 50 yards, shooting off a bag on my truck’s hood, I didn’t do so well. I shot the G40 MOS on two different days, and this was the second day. The best I could muster: 50 percent on a 6” target. That’s not good, but considering how well it did at 25 yards, I’m guessing it was user error. My better groups were sub 3” at 25 yards, so I would have thought more would be in the target zone at 50 yards. What can I say, some days the bear eats you.

What disqualified the FNX-Tactical from the truck gun contest – my search for a gun that can ethically harvest game and will work for concealed carry around town – is also a problem for the G40. On a 1911, a 6” slide looks long. On this GLOCK, it looks like a harpoon over the trigger guard. The large frame is already hard to conceal; that runway-length slide makes it almost impossible. Almost.

I do a bit of leatherwork and I mocked up a few holsters for the G40 MOS. With a light jacket and the right cant, the 10mm GLOCK is reasonably concealable. But – hidden like that, I’d never be able to draw it when seated. And not quickly from any position. That doesn’t detract from how well the gun performed, but it does put it does make it questionable as a truck gun contestant. GLOCK G40 Gen4 MOS Pistol

I still think every American should own a Toyota Corrola and a G19 at least once in their life, just to see that “good enough” really is pretty good. But the G40 MOS shoots like a different beast altogether. It’s the first GLOCK I’ve shot particularly well. If I can figure out a way to holster it, it will have taken the STI Nitro 10 review, as front runner as my co-pilot.

Specifications – Glock 40 Gen4 MOS

Caliber: 10mm auto
Operation: Double-action
Magazine: 15 rds.
Weight: 28.15 oz. (empty)
Barrel Length: 6”
Overall Length: 9.49″
Sights: Fixed 3-dot
MSRP: $799

Ratings (out of five stars):

Style * * *
I don’t like the way GLOCKs look and this one is no different. I don’t know whether to take a star off or add one for the plank-like slide.

Customization * * * *
The gun includes backstraps and the optics mount, which is great. The lack of an option for night sights that would co-witness and a threaded barrel (why not add another ½” at this point) would give it a five-star rating.

Reliability * * * * *
It’s probably unfair to give the gun any kind of reliability rating with only 200 rounds through it. But I had zero malfunctions of any kind while firing in any position with any ammunition I used.

Accuracy * * * *
Once the RMR was removed, very good. And plenty good enough for hunting in the thickets. The trigger reset is exceptional. GLOCK G40 Gen4 MOS Pistol

Overall * * * *
If you’re looking for a relatively inexpensive hunting gun, it would be hard to go wrong with the G40. Taking anything up to black bear, I’d be confident with this gun out to 50 yards with any of the rounds I shot. The ability to carry a lightweight polymer frame pistol and still put 15 rounds of 10mm down into the breadbasket at reasonable handgun hunting distance makes this a powerful tool indeed. GLOCK nailed this one.


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