Glock G40 Gen4 – aka Glockzilla, is a 10mm Masterpiece

Way back in 2015, Glock unveiled a new pistol that flew a bit under the radar as people were clamoring for a Glock Carbine or a single stack 9mm.

That pistol was the Glock G40 Gen4 in 10mm with a 6″ bbl and 9″ slide, which had the company’s new, at the time, MOS option (modular optic system).

We might still be waiting on the carbine, and the single stack came out just prior to the NRA show earlier that year in the form of the Glock G43 Handgun, so we decided to try out the G40.

This model is the most powerful Glock pistol in existence and the biggest one the author has handled (the G41 in 45 ACP is the same size); so much so that we started calling it GLOCKZILLA at the beginning of the test period.

About the 10mm Round

For those who are unfamiliar with the 10mm round, here is a short history.

Dissatisfied with the performance of the 9mm cartridge in the 1970s and 1980s, a round was sought that would replicate the ballistics of the 357 Magnum round in a semi auto pistol. The result was the 10mm, but due to the pressure of the round, most existing platforms could not be used.

A larger framed pistol based on the CZ75 was the first candidate (known as the Bren Ten) and the 1911 frame was adopted in the form of the Colt Delta Elite in 1987.

When the FBI decided to adopt the round, Smith & Wesson adopted their double action 45 pistols to chamber the round in 1989, Glock followed two years later with their G20 Pistol.

Alas, the agents of the FBI found the recoil too harsh and a new round was created (40 S&W) with a reduced load and a shorter case that allowed the round to be chambered in 9mm sized pistols.

The 10mm cartridge would have perished had it not been for a large fan base that cherished the qualities of the round for hunting and the sheer power factor of near Magnum handgun performance in a semiautomatic pistol.

Shooting the Glock G40 Gen4

We headed out to the range and set up targets expecting the Glock G40 Gen4 to perform like the author’s Gen 2 G20: a lot of noise and felt recoil.

We were totally shocked when the slide did not seem to rise at all.

A variety of loads went through the pistol, from lightning-fast 125-grain bullets to heavy 200-grainers, and not only functioned flawless, but accuracy was impressive, with groups averaging 1.75” at 50 yards. There was only one problem.

It felt like no other 10mm pistol we had ever fired with regard to recoil.

Three decades of weekly shooting will probably numb you to most handguns, particularly if you regularly shoot 45 ACP, 10mm, 41 Mag, 45 Colt, and 357 SIG. So, we were hesitant to mention this in a review until we let a couple of friends try the Glock G40 Gen4.

They were shooters, and only one was familiar with the 10mm round. Both stated that it felt more like shooting a 9mm.

Not the answer we expected to hear when the magazine was loaded with sub-41 Magnum loads!

Glock G40 Gen4 – The good

There is a lot to love about this pistol if you are a fan of the 10mm cartridge.

The grip frame is the SF (Short Frame) size to accommodate most hands and two larger back straps and two beaver tail extensions can be used to make it larger if need be.

Glock triggers are often lampooned when compared to non-striker fired pistols and are often candidates for replacement, but the Glock G40 Gen4 trigger breaks at 4.5 pounds. Rather than replace it, we opted for a light polish on the inside.

Perhaps the most significant improvement is the MOS system giving the shooter an option of a good number of aftermarket reflex type sights without expensive milling and of course being locked into one type. If the Trijicon RMR does not work for you, swap it out for a Leupold Delta Point in a matter of minutes. We regret that we did not get a chance to test with a holographic sight, but that may change in the near future.

Finally, the six inch barrel gives enough of a boost to the 10mm cartridge to make it memorable. We do not quite put it in the category of the 41 Magnum class, (although ballistically it would match up to a similar cartridge fired out of a shorter barreled 41 Magnum revolver), but it definitely exceeds the power of a 357 Magnum with a bullet that is 1mm larger in diameter. That and you get 16 rounds as opposed to 6.

Glock G40 Gen4 – The bad

If there is one drawback to the Glock G40 Gen4 or any of the MOS models, it is a number of extras you get with it. We have no idea how everything fits in the box, but there’s 3 15-round magazines, paperwork, fired cases, a multilingual instruction manual, spare back straps and beaver tails, a tool for installing them, magazine loader, cleaning kit and 4 MOS mounting plates.

Extras are not a bad thing, but finding a place to put them can be (lose that 43 mag loader and if you ever try to sell it they will ding you for $50 for not being “complete”). Luckily we had a spare old school Glock “Tupperware box” to stash the extras for safe keeping.

A minor complaint may be the sights. As most Glock owners know, the factory plastic sights are “place holders” until you pony up for metal night sights. With a pistol like this running a factory rear adjustable sight, we feel Glock could have gone the extra step with a taller sight to co-witness with the optic.

Live Inventory Price Checker

	Glock G40 Gen 4 10mm Pistol MOS 6" 15rd - UG4030103MOS	Palmetto State Armory	$ 947.99 $ 700.99
	Glock G40 Gen 4 10mm Pistol MOS 6" 15rd - UG4030103MOS	Palmetto State Armory	$ 947.99 $ 700.99
	Zaffiri Precision Upper Parts Kit for Glock Gen 4 G19 - Precision Upgrade Kit for Glock 19 Gen 4 - 19.4.UPK	Palmetto State Armory	$ 125.99
	Zaffiri Precision Upper Parts Kit for Glock Gen 4 G19 - Precision Upgrade Kit for Glock 19 Gen 4 - 19.4.UPK	Palmetto State Armory	$ 125.99

Glock G40 Gen4 – The Reality

The G40 is the softest shooting 10mm pistol we have fired in over 25 years of experience with this cartridge. We believe this mostly has to do with the length and weight of the slide absorbing the brunt of the recoil.

They may not have been the first company to build a 10mm, but the G20 was one of their first designs and they have stuck with the cartridge where many others have given up. The G20 is the 10mm handgun with the longest continuous production history on the market coming up on 25 years and the Glock G40 Gen4 is its younger and bigger brother.

Glock has a winner with the Glock G40 Gen4, but the market segment will mostly be handgun hunters, 10mm fans or the Glock collectors who must have one of every model that Glock puts out. Glock touts it as a competition pistol, but we think that it may be too big for some league’s rulebook to be a serious contender in that market.

Most 10mm handgun reviews state that the round is not for everyone, and this is true. However, the Glock G40 Gen4 may be an exception to that rule due to the minimal recoil impulse when compared to other handguns in that caliber.

As a reviewer, the author tests many firearms. At the conclusion of testing, most are sent back to the manufacturer.

The Glock G40 Gen4 is the first review gun of any kind that the author has decided to buy for his own personal use. It is simply that good.

Now all they need to do is build a similar sized model in 357 SIG.

Glock G40 Gen4 Resources:

• Glock’s G40 Gen4 Product Page
• 10mm Ammunition
• Assorted Glock G40 Gen4 Handgun Videos

About Mike Searson

Mike Searson’s career as a shooter began as a Marine Rifleman at age 17. He has worked in the firearms industry his entire adult life as a Gunsmith, Ballistician, Consultant, Salesman, Author and was first certified to teach firearms safety in 1989.

Mike has written over 2000 articles for a number of magazines, websites and newsletters including Blade, RECOIL, OFF-GRID, Tactical Officer, SWAT, Tactical World, Gun Digest, Examiner.com and the US Concealed Carry Association as well as AmmoLand Shooting Sports News.

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