The initial Glock G20 and the evolved and supersized G40 really came to be due to a 1986 Miami FBI felony car stop of two armed bank robbers. The net of that very bloody 140-plus-round bullet exchange over four minutes between the robbers and 10 carloads of FBI agents was that the FBI felt woefully undergunned with the then-standard .38 Special, .357 Magnum, and 9mm handguns. What followed was a deep 360-degree analysis of nearly every aspect of the event, including a number of recreated videos, which all lead to adapting the much more powerful 10mm Auto handgun round for more penetration and stopping power — at least briefly.
Glock rushed the G20 to market in an attempt to capture the FBI contract, which they did — briefly. The Glock G20 was one of the first high-capacity handguns for the fairly new Norma-produced 10mm Auto round, led by Jeff Cooper’s involvement. Cooper designed the 10mm Auto based originally on a cut-down .30 Remington rifle round case with the goal of delivering better ballistics, flatter trajectory and more range than the .45 ACP round. The FBI’s interest was in the round’s ability to punch through barriers and still deliver devastating stopping power.
Though the 10mm Auto delivered huge power in a semi-auto handgun, the power ultimately was deemed too much to handle for the majority of FBI agents, and the original G20’s heroic grip proportions simply were not comfortable for the vast majority of agents. With the addition of 50% more power than issued .38 Special, .357 Magnum and 9mm rounds, the 10mm’s power and size were just unfeasible for most agents to handle and shoot accurately, with many rumors that agents could not pass shooting qualifications with the gun.
Because of the now-known flexibility of the G20 to consume everything from light to powerhouse loads, the FBI attempted to issue 10mm Lite rounds that dropped the energy to about 400-500 fpe (ft./lbs. of energy). Smith and Wesson believed the unused case capacity was a waste and created a shorter 10mm-cased round named the .40 S&W, ultimately delivering a round that today offers about 380 to 500 fpe. FBI agents found the lower-power .40 S&W rounds controllable and the smaller-grip-framed G22 and compact G23 comfortable to shoot. Fortunately, the legacy of the 10mm Auto did not stop there.
Over the years, that same brutish power of up to 780 fpe with big 15+1 capacity is the reason there is a cult-like customer demand for Glock’s venerable 10mm Auto. Despite being a cast-off cartridge by the FBI, the round is beloved by power-hungry customers, who appreciate the comparatively soft-shooting characteristics that the Glock design delivered in the G20 and a newer SF (Short Frame) version that offered a G20 with the same grip dimensions as the .40 S&W G22 and G23.
Over time, the G20 became a go-to gun for wilderness outdoorsmen as a viable solution for protection from bears and large wild game attacks, with more than twice the rounds of a typical revolver. Fast-forward to an exponential growth of handgun hunting, and the G20 has become a handgun hunting favorite, with plenty of power and capacity. Hog hunters added red-dot optics and even pressured aftermarket match barrel manufacturers, like KKM, to offer extended 6-plus-inch barrels to squeeze even more power out of the compact format. The G20 continued to be a hit for wilderness and dense brush hunters who needed a maneuverable high-capacity firearm with lots of power. Glock paid attention and introduced the Gen 4 G40 MOS in 2015 but at such a limited supply that there remains a healthy demand today for Glock’s most unusual model.
The G40, aka “Glockzilla”
As if the G20 format was not already big enough, the G40 MOS grew to heroic proportions. It sports an even longer 6-inch barrel and slide for a bit more velocity and power. Thanks to Glock’s highly flexible MOS system, the G40 is ready out of the box for mounting of nearly any red-dot optic on the market. The enormous proportions of the Glock G40 earned it the name “Glockzilla” by 10mm fans. There is more to the size than what is initially apparent to customers. The G40 MOS carries over the smaller SF grip frame sizing to fit less Hulk-sized hands but still allows for grip customization as needed.
The size, weight, barrel length and updated Gen 4 dual recoil spring also mean this 10mm monster has less perceived recoil than the G20 models. During over 100 rounds of testing with standard to heavy full-power Federal and Hornady rounds, the G40 was, in fact, quite fun to shoot, with noticeable recoil reduction compared directly with a G20SF. Where the G20 can be a bit harsh to shoot with full-power 10mm hunting rounds, the G40 is very pleasant, all while being more accurate in the process. If customers want to shoot 10mm a lot, this is definitely the gun for them.
Like the long-slide G34, G35 and G41 competition models, the G40 delivers more stability when precision is required. There was a noticeable accuracy improvement compared to the G20 with steel-sighted offhand shots and with the added Burris Fastfire 3 red-dot, 100-plus-yard steel gong shots were so boringly easy we started banging away on the 300-yard gong after figuring out the right holdover. Notably, the included MOS system and adapter plates provide dealers packaging or instant sales opportunities to add on a red-dot optic for the customer.
The two extra inches of G40 barrel length deliver a bit more velocity, with most shooters reporting about a 10% increase in energy depending on the round. This may not seem like a lot on paper, but in reality, adding 10% to the typical 650 fpe round pushes the power into the 710+ FPE range.
Selling the Full Power of the 10MM Auto
There was a period where most of the 10mm rounds were designed around the FBI 10mm Lite requirement and delivered marginally more than the .40 S&W, but thankfully, that has changed. The current crop of 10mm Auto rounds from Hornady, Federal Premium, Liberty, Buffalo Bore are regularly delivering 650 ft./lbs. of energy, with some specialty ammunition like the Liberty Civil Defense achieving 2,400 ft./sec. and a whopping 780 ft./lbs. of energy with a 60-grain alloy bullet. The Buffalo Bore rounds use a typical 180-grain JHP and still deliver 1,350fps and 728 ft./lbs. in their Heavy 10mm Pistol ammo.
For handgun hunting and wilderness defense, those super-hot rounds are not really optimal for controlled penetration on potentially dangerous game. Most 10mm hunting-tuned rounds average about 500-650 fpe with bonded JSP, copper alloy or monolithic bullets for deep, reliable penetration. Buffalo Bore, Federal Premium and Hornady all offer hunting specific rounds. Regardless of the round, the Glock design and G40 proportions really soak up a significant portion of that recoil.
Carry Options
Generally the G40 will fit any of the existing open-ended G20 holster options on the market, however, the 2-pound weight is felt when carried on the hip. Considering the purpose of this gun is likely hunting, hiking and trail defense while carrying a pack, a chest-carry rig like the GunFighters Inc. Kenai holster is an incredibly comfortable, accessible and fast-drawing option. The Glock 40 MOS carrying in the Kenai chest holster was tested on several hunting and hiking trips, and the comfort was so amazing I ordered a second Kenai for my Glock 17. Typically this size and weight of firearm is difficult to carry concealed and even more difficult to access in a strong-side carry buried under layers of hunting clothes. The 3 or 9 o’clock carry weight of a standard holster can also throw off the stride and gait of a hiker. The idea of the Kenai holster is to get the gun into an accessible position outside clothing without interfering with a pack or throwing off a hiking gait. The nice benefit is with a pack on there is a bit of appreciated weight distribution a chest-carried gun delivers. The Kenai would be as natural an accessory to purchase as an appropriate red-dot sight for G40.
The Glock G40 MOS delivers a wonderful format for delivering very high-energy rounds stacked 15+1 high. The 10mm Auto has stood the test of time and now proven itself as a viable hunting and self-defense round. Whether customers want the ultimate gun for hunts or simply the most powerful high-capacity handgun on the market, the G40 MOS is worth having on the shelves.
