The year is 1990 and the world is looking into new cartridges to fill the gap in stopping power for law enforcement use. 7 years prior, the 10mm auto round was originally conceived by Jeff Cooper to be used in the Bren 10 handgun.
This new ammunition was the theoretical solution that cops needed to equip themselves with a fast-moving high caliber projectile capable of pacifying a human target.
Although the Bren 10 was a commercial failure, the 10mm auto sparked enough attention for other manufacturers to develop their own designs.
Flash forward to 1991 and the first Glock 20 10mm auto pistol rolls out of production, ready to take on the task as a duty handgun.
The release date puts the Glock 20 right in the middle of gen 2 production and at a similar time as the Glock 21, another big-bore offering in 45 ACP.
To accommodate the larger round and higher pressures created by firing, the Glock 20 was designed to be longer (0.1 inches) and wider (0.3 inches) than the Glock 17.
The barrel and slide were also made thicker to contain the power of the large, fast-moving round.
Interestingly, the Glock 20 shares close to 50% of the parts used on the Glock 17, so many interchangeable things.
The Glock 20 is shipped by default with a double-stack magazine that holds 15 rounds with an option for 10 round mags where regulations require a lower capacity.
Unfortunately for Glock, the popularity of 10mm quickly deteriorated due to the FBI and other agencies moving away from the caliber in favor of the smaller .40 S&W cartridge. Due to the sheer force that the 10mm dished out, it was not very highly regarded by smaller framed people and the FBI even started using reduced recoil loads before giving the caliber up.
But all was not lost. Recently there has been a renaissance of 10mm popularity and it has even started to see some newer gun offerings.
It has become a respected option for pistol hunters or even as a backup for shotgun/rifle hunting since 10mm is capable of dealing a humane culling shot even on larger animals.
Features Of The Glock 20
The Glock 20 is a semi-automatic pistol that uses a locked-breech, short recoil action with a tilting barrel.
The slide is held onto the frame by slide guides as opposed to traditional frame rails to improve reliability.
Another unique feature used to increase reliability is that the trigger force is used to rearm the striker. This allows the recoil spring to have an easier time moving the slide back into the battery.
In addition, this effectively allows the recoil spring to focus more heavily on allowing the next round to enter the chamber from the magazine even when the gun is thickly fouled.
Many pistol components, including the frame and magazine shell, are created using a nylon-based polymer invented by Gaston Glock and coined as Polymer 2.
This material was specifically created to resist shock, liquids, and temperatures while being more durable and resilient than carbon steel and steel alloys.
Ease of maintenance was an important aspect when developing the Glock pistols. To disassemble the gun to its significant components, all that you need to do is the following:
Remove the magazine and clear the chamber.
Point the gun in a safe direction and pull the trigger.
Pull the slide back approximately ¼ inch and hold it in place.
Pull down the take-down lever and let the slide go forward.
Gently allow the slide to move forward off the frame.
Remove the recoil spring & assembly.
Remove the barrel.
All Glocks also use a striker fire system. Unlike a traditional single action or double action handgun, a striker-fired pistol has consistent trigger pull throughout the course of fire without the external moving parts that could break or get caught on something.
Glock pistols are designed with three independently operating safeties. The system is designated as the "safe action system" by Glock.
This system consists of integrated trigger safety, firing pin safety, and drop safety.
All Glock handguns use polygonal rifling as opposed to traditional lands and grooves. This fabrication method allows the thickness of the barrels to remain more consistent than lands and groove rifling. The result is a better gas seal leading to more consistent muzzle velocities, increased accuracy, and ease of maintenance.
Glocks have a low slide profile allowing the barrel to sit closely in line with the shooter's hand. This allows the gun to have less muzzle rise to let users rapidly get their sights back on target.
The standard factory sights that come with most Glocks are fixed polymer. The front sight is ramped with a white dot while the rear is notched with a white goalpost outline.
In my opinion, there are metal night sights and tritium sight upgrades available both from the factory and aftermarket that can drastically improve the standard sighting configuration. Changing the sights would be especially useful if the gun is going to be used for hunting purposes.
117mm | 4.61 inches
Weight (without magazine):
780g | 27.51 ounces
Weight (with empty magazine):
870g | 30.69 ounces
Weight (with loaded magazine):
1130g |39.86 ounces
28N | 5.5 lbs
205mm | 8.07 inches
Height (incl magazine):
Line of Sight:
Glock 20 Generations
The first Glock 20 came off the production line in 1991 during the gen 2 era. Although it was not available during the beginning of the gen 2 release, the Glock 20 was ready to fill the void of a reliable 10mm gun that professionals were looking for at the time.
Gen 2 Glocks were given upgraded texturing on the polymer frame that allowed the shooter to maintain a stronger grip in the frame during the course of fire. The older gen 1 became slippery when the gun or the users' hands became wet while shooting.
Both the front strap and trigger guard were given this upgraded checkering texture while the backstrap was serrated as well as checkered.
Since the gun debuted in 1991, all Glock 20s will come with the integrated recoil spring assembly that replaced the two-piece recoil spring and assembly that year.
Generation 3 was introduced in 1998 and came with more changes to the pistol for better and for worse.
Gen 3 was when the Glock Accessory Rail was introduced, so you could now easily attach a laser or light to your handgun.
A thumb rest cut into the polymer frame made it more natural for a hand to grip.
The most infamous of "upgrades" during gen 3 was the finger grooves. Although these grooves added grip and felt comfortable to some, they were more of a hindrance to others, especially to people with smaller hands.
There were some internal improvements added to the pistol around the halfway point through this generation's lifecycle.
The first was that the extractor was modified to also act as a loaded chamber indicator.
The second was the addition of a locking block pin added to take some stress of the locking block when the gun was fired. The locking block was also enlargened to further help with the rigidity of the firearm.
The gen 3 Glock 20 was also given a short frame (SF). This design reduces the overall size of the grip by removing material from the rear. This makes it much easier for people with smaller hands to use and control the gun.
Gen 4 was released in 2009 (2010 in the United States) and saw many improvements to the Glock pistols. This generation also allowed the end-user to start customizing their gun to fit their hands even better right from the factory.
Starting off, this is the generation that introduced the interchangeable backstraps. These backstraps allow the user to choose between a small, medium, or large backstrap to more comfortably control the firearm when shooting.
The magazine release was reengineered to be reversible from the left and right sides of the frame. This is a huge advantage for left-handed shooters who had to reach around the grip to drop the old mag.
The magazines for the Glock 20 gen 4 also needed to be changed to accommodate the new mag catch. The notch cut on the left side now wraps around the front of the magazine and goes all the way to the right-hand side, so no matter what side the catch is located on, the magazine will lock in place.
A double recoil spring is used on the Glock 20 gen 4. This is a huge improvement for big bore calibers like 10mm since it noticeably dissipates recoil. So now you can have a 10mm semi-auto pistol with a 15 round magazine AND reduced felt recoil. That put the G20 pistol in a pretty unique place.
Furthermore, the gen 4 saw improvements to the frame with enhanced rough texturing. This significantly improves the gun by making it easier to keep a good grip while shooting.
Unfortunately, as of the time of writing this article, there has not been a gen 5 Glock 20. The release of gen 5 has been coming out in phases, with 9mm offerings being in the center stage when the generation was first launched and the .40 S&W followed suit the year after.
How Does The Glock 20 Compare To Other Glock Models?
The Glock 21 is a full-size big-bore pistol chambered in 45 ACP, very similar to the G20. They released around the same time and have since scratched the itch for a large caliber pistol for self-defense and duty.
I have shot both of these pistols side by side and the weight and form factor of the two is very similar. They both have an overall length of 8.07 inches and a barrel length of 4.61 inches. The G21 may have been a little heavier due to the 230-grain bullets vs. the 10mm's 180 grain at the time but the difference wasn't very noticeable.
The velocity difference is apparent though, when firing the 45 ACP, you can visually see the bullet travel down range but you can't do that with the 10mm.
If you like the idea of the G21 but also think that you would only ever use it at the range or might be thinking about a significant caliber for competition, then the Glock 41 might be for you.
This thing is a monster with a longer sight radius, adjustable sights, and better trigger. It's everything you need.
If you like the idea of having a 10mm gun for self-defense, then you will love the Glock 29. Think of it as the subcompact version of the full-size G20.
With a 10 round magazine with the option to use the 15 round found on its bigger brother, the G29 really packs a lot of pouch in a moment where you might really need it.
If target shooting is more your thing, then the Glock 40 might be the gun for you.
With an overall length of 9.49 inches and a loaded weight of 44.62 oz, it is a really big boy. With a barrel 6.02 inches long, you can ensure that accuracy will be best in class compared to other Glock models. It is just as long as target revolver barrels.
To be fair though, a semi-auto handgun this size, weight, and width will need getting used to; if you have big hands like me, it may not be a big deal.
Glock 20 Competitors
Sig Sauer 220
The Sig Sauer P220 comes in two 10mm flavors that directly compete against the G20 in two different departments.
The P220 Hunter is designed with, you guessed it, hunting in mind. This gun comes from the factory, rocking a Kryptek camo pattern, a fiber optic front sight, and a fully adjustable rear sight. The slide and frame are made of stainless steel, helping with weather resistance. The pistol comes with a 5-inch match-grade barrel and fires single action only.
It's no surprise that this gun is a great choice to carry for hunting purposes.
The second contender is the P220 Legion. The Legion comes either in single action only or DA/SA. IT is a full-sized duty pistol with an accessory rail and night sights. The frame and slide are also made of stainless steel with a unique legion gray finish.
The Springfield XDM is another polymer frame handgun available in 10mm that competes with the G20.
It features interchangeable backstraps, a beavertail safety on a striker-fire system, accessory rail, fiber optic front sight, 15 round magazine capacity.
The XDM has an overall length of 7.7 inches with a 4.5-inch barrel and weighs 31.2 ounces.
Popular Glock 20 Accessories
Glock pistols are well known for having a ton of aftermarket accessories available and the G20 is no exception.
I would first change the sights on the gun for a pair of quality steel night sights. They are less likely to break and give you enhanced usability in low-light situations.
The next thing I would change is the trigger. Prior to gen 5, the Glock triggers left a lot to be desired. The aftermarket scene developed plenty of great options to give you either a competitive edge or a consistent trigger you can count on in defensive situations.
Extra mags are never a bad thing. The factory mags work very well and are a reasonable price if you need more.
A laser or light would also give you extra usability in low light and is a great addition to have. Most holsters on the market will not be compatible with something taking up rail space but most quality brands of rail accessories are easy to remove if need be.
Ammunition for 10mm
Whether at the range, in the wilderness, or when it really counts, there are plenty of great ammo options for 10mm pistols.
I have found the Federal American Eagle 10mm 180 grain to be the easiest to find at my local shops and since my local area doesn't tend to stock crazy amounts of options, it is what I use. It works well and is a reasonable price.
Using the same grain weight as your fun time ammo is important when selecting a defense round. Luckily, Federal has us covered with their 180 grain Hydra-Shok. This is incredible ammunition and although it does come at a high price, I'd rather put a few extra dollars into ammunition that might be used to save a life.
Federal also has us covered again for hunting ammo with their 180 grain Vital Shok. This ammunition uses their awesome Trophy Bonded jacketed soft point that will reliably handle a medium and even larger game with impressive expansion while being tough enough to puncture thicker hide and bone.
Closing Thoughts and Summary
If you have made it this far, thank you for sitting through my review.
The Glock 20 is a great handgun choice for those who like a full-sized pistol with the bold personality of the 10mm cartridge. It is a fun gun to shoot and you will be turning heads at the range when they see the size of the brass ejecting from the gun.
With a 15 round ammunition capacity, you will not be sacrificing many rounds compared to smaller caliber pistols.
An impressive aftermarket follow allows you to customize the gun to your personal preference and enhance some of the less desirable features included on the pistol from the manufacturer.
Thanks again for your time and enjoy the rest of your day!
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