Gun Review: Glock 40 Gen4 – A 10mm Long-Slide Red-Dot Big-Bore Hand-Cannon

Nathan S
by Nathan S

Off the bat, I would call this the F-350 of handguns. Its a ridiculous amount of handgun for most everyday users and one would typically not drive one into the city. Its just unwieldy. But, there is a reason F350s are made as there are users who know what they need to get a big job done. That may be heavy payloads, hauling long-distance, or simply hauling *ss.

Glock puts it this way:

The G40 Gen4 in the MOS Configuration is chambered in 10mm and combines a full 6-inch barrel for an improved velocity with a magazine capacity of 15 rounds. The G40 Gen4 in MOS configuration is a powerful yet easily carried pistol; perfect for the outdoorsperson, hunter and sport shooter. It is designed to give the handgun hunter the ultimate choice in semi-automatic gaming pistol and has proven to be more than capable of taking down game such as Whitetail Deer, Russian Boar and even Feral Hogs.

What Comes in the Box:

The new Glock handgun cases are a huge step up, but I would contend the G40 has outgrown it. Opening it up, the case nearly popped out due to the contents. Everything will go back into the case, just make sure to brush up on one’s Tetris skills.

  • G40 Gen 4 w/ 15 Round Magazine Inserted
  • 2x Spare 15 Round Magazines
  • Spare Medium & Large Backstraps in Standard & Beavertail Form
  • Magazine Load Tool
  • Glock MOS Mounting Plates for Common Micro Red-Dots
  • Factory Test-Fired Rounds for Restricted States
  • Adjustable Sight Tool
  • Child Safety Lock
  • Cleaning Brush
  • Paperwork (Manual, Warranty Cards, Etc.)

Overview & Handling

I expected the Glock to be heavier considering its size, but it was a gentle giant at just over 28 ounces. Now, I would not call it graceful, even for its size. Unloaded, the pistol is front-heavy from the long-slide, but upon insertion of the magazine it starts to balance out (about 40 ounces). Its not until the red-dot is on the top that I found it suitably neutral for extended shooting sessions.

The grip itself is massive. Those with small hands need not apply, even without the back-strap. My wife, who can reasonably hold a medium back-strip G17 9mm found it difficult to simultaneously get a firm grip and reach the trigger. My medium-sized hands found the smallest setting most comfortable, but the medium back-strap most assuring, as I tend to grip high on a gun and get slide-bitten. Unlike other Glock competition-oriented handguns, the G40 does not have the extended slide stop.

I am sure it will be mentioned a few more times, but for handing purposes, its a Glock Gen 4. The grip includes finger groves (which work for me), the square textured grip pattern (which I also like), larger and reversible magazine release, and a too shallow undercut on the trigger guard for the middle finger. It arrives with standard adjustable Glock sights (which work, but are terrible) and interestingly, the rear sight actually overhangs the back of the slide a bit. Not sure if this is an engineering oversight, but its annoying for “perfection”.

Sight overhangs the rear just a tad.

The MOS System

The MOS system or “Modular Optic System” is a latest and I found surprising addition to the Glock family. Introduced with the G40 and 9mm/.40 smaller siblings, its a from-the-factory optics mounting cut into the slides. This is by no means innovative, as the aftermarket has been doing it for years, but it is useful and actually helps “perfection” get closer to perfection.

Author’s Note- It was disappointing the PFI optic sent separately from Pride Fowler was not compatible with the MOS system. While set up for one of the patterns, the optic sits too far forward to actually be nestled into the handgun slide as intended. I got my hands on a Trijicon mini-dot to test the MOS system (not pictured).

Drop plate on, drop optic onto plate. Its that easy.

Typically, those wanting the functionality had to either buy an aftermarket slide, send it off for milling, or use an adapter plate which sets the optic up higher. Having this done at the factory lends has at least a few advantages. When already loaded in a milling machine, its easy and inexpensive to add the cuts, the cut-out area can be coated instead of being left bare, and ensures tighter tolerances than separate machine loadings.

Just quite didn't fit.

The MOS mounting area sits just fore of the adjustable rear sight. As shipped, it arrives with a flush and profiled plate that matches the slide. The blending is excellent and only those with solid eyes or handing the firearm up close would notice that it could accept an optic. The plate is held on with two torx head screws and removes easily to mount an optic. Adapter plate mount to slide and the chosen optic to adapter plate. Voila.

Once mounted, it brings up another gripe. The factory sights are way too low for any sort of co-witnessing. Considering the cost to injection-mold these, another oversight from Glock. I know there are plenty of aftermarket systems out there, but at least Glock could have made the effort.

Shooting the G40 Gen 4

If one has shot 10mm before, there is nothing truly remarkable about the Glock’s performance. The cartridge, to me, is just like its daughter the .40 S&W. There is some snap to the recoil, which the dual spring and heavier slide do help soak-up, but its not so much that I could go on another paragraph.

Accuracy continues to be normal for my abilities with a Glock, but the longer sight radius did help tighten it up a bit, to just over 1.5″ at 15 yards (Freedom Munitions 180 grain RNFP) using the iron sights (I normally shoot about 2″ with a G19). Adding in the optic (provided by PFI – detailed review coming later), I was able to shrink it some more, shooting 2.0″ at 25 yards.

As with nearly any review written on a Glock, the trigger is long, mushy, and a solid Glock. However, I am not a fan of this one, as Glock opted to remove the serrations found on most of their other handguns. This truly accentuates the passive safety, which after about three magazines actually started to cause discomfort in my trigger finger. After a 100 rounds, I utterly detested it. Of course individual preference will rule the day, but this is one Glock that in my opinion, needs an aftermarket booger-switch.

Various groups while out on the range. Top right is at 25 yards, offhand, slowfire. Impressive.

Putting aside the trigger, the MOS system truly shines on the handgun. True to Glocks intended purpose, adding in the optic makes this a “long” range handgun with true hunting potential. For older eyes or simply faster target acquisition on moving targets, the red dot on the handgun shines. With either excellent trigger control or a better bang-switch, the G40 can and does meet Glock’s claims for an excellent hunting handgun.

I will note, though, that to take maximum advantage of the longer barrel hand-loading will be required. Factory 10mm loads tend to be “neutered”

Author’s Note: While Glock specifically disclaims the practice, shooting .40 S&W through the 10mm was possible, if not more pleasurable due to the better slide to powder-charge mass ratio. Glock states this will void your warranty and rightfully so, as one is shooting a round outside of proper head-spacing. TFB and myself DOES NOT recommend this be done at home.

25 yards, fast-fire, off-hand. Full Magazine.

The Good:

  • MOS system is fantastic. Works as advertised and is nearly future-proof as one only needs to buy new plates.
  • Magazine capacity is 15+1 of a big-bore handgun cartridge.
  • Light, relatively speaking, for the caliber. 10mm 1911s are just freaking heavy.

The Notable:

  • Its a Glock, with all the benefits and quirks thereunto pertaining.
  • Its BIG. Really, really big. My small-handed wife could not even comfortably grab it. Medium-sized hands are a prerequisite.
  • Did have the occasional difficult putting it back together.

The Bad:

  • Trigger is smooth-faced, except for the passive-safety, which makes it detestable for long firing sessions.
  • A few annoyances: The rear sight overhang, and the lack of extended slide stop.

Final Thoughts:

The problem with reviewing Glocks is that they are Glocks. There really is never much new about them so writers are left searching for prose. This one is no different. The G40 Gen 4 is a Glock at its core, just a very big one. Its a great handgun for those who want or need 10mm. If you don’t need 10mm, the trade-offs to get there with the bigger grip and massive size are, in my mind, simply not worth it.

On the other hand, the MOS system for optics mounting is much appreciated and a solid step forward for the notoriously conservative Glock company. With simple plates to mount to just about every conceivable micro red-dot (just not the PFI), its a versatile system that worked well, although I am curious to see how various red-dot systems handle the increased recoil.

Ultimately, the combination of the two makes this a novel Glock. Its a veritable hand-cannon with the 6″ long barrel (although one needs to reload to take full advantage of this length). Further, its reliable, the trigger sucks, and it can mount a red-dot sight without having to find an aftermarket slide or mounting accessory.

So, if you need this much gun, its a solid super-duty. If you don’t need this much gun, go with the smaller option, you will be much happier.

Nathan S
Nathan S

One of TFB's resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR's, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.The above post is my opinion and does not reflect the views of any company or organization.

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