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Glock 21 Review: Bringing .45ACP to Glock Platform

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A .45 Auto Handgun Other Than A 1911?

By Carlos Huerta

When people say they want a .45 ACP pistol, most people automatically think of the 1911 pistol, but did you know there are other options with higher ammunition capacity? The Glock 21 was the first of its kind to offer 13+1 rounds of .45 ACP. It’s also one of the most affordable .45 Auto handgun on the market.

Are you looking for a .45 caliber handgun that provides all of the power you’d expect from a .45 but without compromising high quality? If you’re a fan of Glock and the .45 caliber then this could be a good firearm for you. The Austrian-made Glock 21 pistol with a polymer frame is simply a scaled up version of the original Glock 17. It’s that Glock shape that everyone either loves or hate. If you’re use to the size on the Glock 17, then the G21 is just slightly larger. The Glock 21 weighs more than other full-sized Glocks but is still lightweight for a .45 handgun. Let’s take a closer look at what the G21 offers.

Table of Contents


Glock 21 Basics

The Glock 21 is the perfect answer to the gun owners who are interested in owning a .45 ACP firearm but love the Glock’s high capacity magazines. It delivers the power of the .45 ACP round with the standard-issued 13 round capacity magazine. The Glock 21 is a full size firearm with a polymer frame. The polymer frame means even with its full size, the G21 fully loaded weighs nearly half a pound less than the steel 1911.

The dimensions of the G21 make it a duty-sized pistol. It’s a double stack magazine that is wider than the 1911, but it’s not uncomfortable to hold. Since the G21 has a higher round capacity, you’ll be thankful that you have an extra round or two if you’re in a situation where you need it. The slide is made of gas nitrate treated steel and the barrel contains octagonal rifling. A component that is common across Glock models is the striker-fired feature which removes the need for a hammer.


The sights are the standard three-dot sights. The sights are well built, precise, practical, and ready-to-go right out of the box. The sights, overall, can come down to personal preference. The lower recoil is a significant advantage. Since the Glock 21 has lower recoil, this means more training with less fatigue. The reduced recoil also offers the ability to accurately fire follow up shots more quickly. Many people regard the G21 as one of the smoothest-firing .45 caliber pistols they’ve ever held.

The one thing I like about Glock is the ability to customize. Glock offers more options for accessory and customization than any other handgun company. There’s so many options for gun owners to tweak or swap out, making their gun their own. The polymer frame features a Picatinny compatible rail and accepts any number of accessories from sights, grips, holsters, lasers, and lights. You could spend hours upon hours adjusting and perfecting your Glock 21.



  • Length (Overall): 205 mm, 8.07 inch
  • Width (Overall): 34 mm, 1.34 inch
  • Height (With Magazine): 140 mm, 5.51 inch
  • Barrel Length: 117 mm, 4.61 in.
  • Weight (With Loaded Magazine): 38.80 oz.

Trigger Pull / In Use

The trigger pull is like any Glock trigger, fitted with a 5.5 lb. pull which is standard. Glock triggers can be heavy and difficult to manipulate but with practice, you’ll get a better feel on it. The trigger pull can initially throw off your accuracy, but it doesn’t take long to become accustomed to it. Reduced trigger weight connectors are available if you want a lighter pull.

Glock pistols also feature three safeties that disengage once the trigger is pressed: the trigger safety, the firing safety, and the drop safety. The trigger safety which is incorporated into the trigger and when engaged, blocks the trigger from moving backwards. The trigger and the trigger safety must be engaged together in order to fire. The firing pin safety is a spring loaded blocker of the firing pin. And finally, the drop safety is a trigger bar prevents unwanted firing from occurring in the event the pistol is dropped. If you like the Glock triggers then you won’t have any problems with the Glock 21.


At the range, the Glock 21 behaved just as a Glock would have. The slide cycle is crisp and smooth. It processes a variety of ammunition with no malfunctions. The Glock can digest anything from bulk practice-grade ammo to imported steel caseloads. All in all, this gun performs great. With 13+1 rounds, the G21 would make a great home defender. Once you learn how to accurately shoot the .45, you’ll appreciate that raw power that most calibers just can’t offer.

You Have The Power But What Else?

What is the biggest advantage of having a .45 ACP pistol aside from the power? Answer: the ammunition variety. There’s so much ammo out there because of the .45’s popularity. Even so, the .45 Automatic Colt Pistol (ACP) round is fairly controversial. Invented in 1905 by firearms designer John Moses Browning, the .45 was the standard caliber of the Colt M1911 Pistol and remains so to this day. This heavy subsonic bullet weighs twice as much as the 9mm round and delivers a third more energy. Today, advances in bullet technology means a 9mm round can deliver as much energy as the .45 ACP. Despite this, the .45 ACP is far from dead, as it has also benefited from advances in ballistic technology. There are more choices of .45 ACP pistols than ever before, as almost all ammunition manufacturers offer several lines in the big caliber.


Another feature you might not realize is you can convert your Glock 21 from a .45 caliber to a 10mm. Converting a Glock 21 to 10mm is simple, after all, the G21 is basically a .45 ACP variant of the Glock 20, a 10mm pistol. The frame is the same and the Glock 21’s slide can accommodate barrels made for the G20. It is essentially a simple barrel swap to change the Glock 21 to 10mm. This said, the 10mm is a substantially more powerful cartridge than .45 ACP. While it’s not quite as big as the .45 Auto. There are a minimum of three things you have to change out to convert the Glock 21 to 10mm: the magazine, the barrel, and the recoil spring. The magazine is the easiest part, just use a stock G20 magazine. Because the Glock 20 and 21 frames are the same, the magazine fits perfectly.

Is It The Right Fit For You?

The size of the G21 makes it an active duty pistol, but the classic polymer frame helps with the weight. Most people don’t have a choice when carrying a duty weapon and are only allowed to carry the caliber their employer or department approves. This said many law enforcement agencies swear by the G21.

If you’re selecting a duty weapon, you’re mainly looking for cost, size, capacity, reliability, and the right fit. If you’re considering purchasing your very first .45 Auto, make sure you do some testing before you make a purchase. I would recommend going to your nearby shooting range to get a good feel of the Glock 21. Comfort is part of what makes some firearms better than others. Take some time to see how the gun feels in your hand. Also, pay attention to the weight, if the grips are slippery or not, and if you can easily reach all the levers with your hand. Some firearms are better at range shooting and others are better for defense. Take some time to think about what your .45 ACP’s primary function will be. If you’re used to firing Glocks, comfortably holding the Glock 21 shouldn’t be a problem. It has the same rectangular shape design that the company is known for. However, if you’re new to Glocks, you’ll need to take some time getting used to the way the gun feels.


Glock 21 Potential Drawbacks

I haven’t seen anything negative about the G21 other then its size. The large frame size requires at least medium size hands to efficiently operate the .45. It can feel bulky and difficult to control if you have smaller hands. I currently have the Glock 21 Gen 3, but I’ve heard that the Gen 4 models are a little bit slimmer and easier to grasp. The Gen 4 offers a modular back strap system making it possible to instantly customize its grip to accommodate any hand size. Other than that, I have not seen or heard of any malfunction problems.

Would the Glock 21 make a realistic concealed carry gun? Yes and no. Because of the size and bulkiness of the Glock 21, I would rule it out as a conceal carry handgun. Plus, the magazines are bulky so if you wanted to carry spare mags, it’s going to add a good deal of weight to your belt. However, many gun owners and law enforcement agencies or those in active military prioritize using a larger caliber, and they are looking for stopping power out of their guns.


Whether you love them or hate them, Glocks have a reputation for excellence that is well deserved. The .45 ACP G21 is no exception. The Glock 21 sets the standard for durability and performance. It offers minimal recoil and provides the same level of durability that Glock has always been known for. It’s durable enough to take neglect and abuse and continue to shoot accurately. It’s a great gun to have and an excellent home defense firearm. If you’re looking for a gun that is known for its dependability, regardless of the stress you put it through, the Glock 21 is your best bet.

The Glock 21 is versatile and can be used for various purposes, including home defense, law enforcement, and target shooting. Its reliability, accuracy, and high-capacity magazine make it a popular choice among gun enthusiasts.

No, despite its powerful .45 ACP chambering, the Glock 21 is known for having manageable recoil thanks to its design and weight. This makes it easier to maintain accuracy even during rapid fire.

Many firearms enthusiasts consider the Glock 21 to be the best Glock chambered in .45 ACP due to its balance of size, capacity, and performance.

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