The .45 ACP cartridge is one of America’s favorites. Designed my John Moses Browning in 1904, the big-bore handgun cartridge served America’s military from 1911 to 1985 when it was replaced for general issue by the 9mm Beretta M9. Some specialized units of the military (including the author’s own Marine Force Recon units) retained custom 1911s chambered in .45. This limited use by special operations outfits further increased the mystique of the heavy .45 round.

In the late-1980s the “caliber wars” were just getting started. The switch from revolvers to the semi-automatic pistol was not yet complete, and debate raged over “light and fast” or “big and heavy” bullets. In one camp were the 9mm fans who swore by the higher capacity afforded by the double-stack magazine. In the other camp were the .45 fans who idealized the .45’s larger frontal surface area saying fuddish things like, “I carry a .45 because they don’t make a .46.” The FBI’s famed shootout in Miami had occurred in 1986 further fanning the flames and causing the introduction of a new cartridge to Glock’s lineup: the 10mm Auto. It was in this environment that Gaston Glock developed the first .45-caliber Glock model.

What is the Glock 21?

Introduced in 1990, the Glock 21 is Glock’s first market entry chambered in .45 ACP. It differs pretty significantly from Glock’s previous offerings. It is one of Glocks “large frame” offerings, with a significantly larger frame than the smaller 9mm Glock 17, 18, and 19. This is to accommodate a double-stack magazine, which became of the biggest selling points of the Glock 21.

The .45 ACP is a fat cartridge, and to make handguns in a manageable size, most manufacturers stacked those cartridges in single-stack magazines with capacities of 7+1 or 8+1. The big Glock 21 held 13+1, giving .45 fans their proverbial “cake and eat it, too.” This made up for some of the Glock’s perceived shortcomings among 1911 fans, such as the use of synthetic materials in its polymer frame, the lack of a manual safety, and its novel (at the time) trigger pull. The Glock 21 gained a fast and loyal following with law enforcement and civilian shooters alike.

The G21 is a full-sized Glock model, intended for duty use. Glock has also released a subsequent version of the Glock 21 known as the Glock 21SF. The grip of the standard 21 is infamously large and sometimes difficult to operate by those with smaller hands. The G21SF was designed to address that, with the SF standing for “Short Frame,” referring to the 21SF’s reduced grip circumference.

Though the .45 is less popular than it once was the Glock 21 is still in service today. Surprisingly, a number of police departments issue or authorize it for use including the police departments of Seattle and Philadelphia. The Glock 21 is slightly handicapped compared to many other offerings from Glock’s catalog. It is offered as the standard, Gen 4 G21, or as the G21SF. Notably absent is an MOS-compatible model so common to other Glock pistols. Both the standard G21 and the G21SF have an accessory rail.

What is the Glock 19?

The Glock 19 is one of the most iconic and popular pistols in America. It is the de facto reigning concealed carry pistol of savvy users and is consistently the top-selling pistol in the United States. The Glock 19 is used by countless law enforcement agencies including the FBI, Secret Service, Department of Homeland Security, D.C. Metropolitan Police Department, and the NYPD. The Glock 19 is even widely used by U.S. Special Operations Forces including Army Special Forces, Marine Raiders, and Navy SEALs.

The little brother of the original Glock, the Glock 17, the Glock 19 is considered a compact pistol. It has a slightly shorter barrel and a slightly shorter grip frame than the Glock 17, both dimensions being ½” shorter. The compact Glock 19 holds 15. The Glock 19 is known for extreme reliability, accuracy, and user-friendliness. It became immediately popular when introduced in 1988 and has remained popular ever since.

The Glock 19 is currently sold in Gen3, Gen4, and Gen5 variants. The Gen3 Glocks have a frame with finger grooves, Gen4s have finger grooves and an interchangeable backstraps, and the Gen5 models having no finger grooves and interchangeable backstraps. The Gen5 guns also have some other upgrades no seen in previous generation Glocks like the carbon steel Glock Marksman barrel, the new compression-based trigger return spring system, and forward slide serrations. All three of these Glock models are available with a light rail and MOS-compatible.

Biggest Differences between the Glock 21 & Glock 19 Pistol

The biggest, most immediately apparent difference between the Glock 21 and the Glock 19 is size. There is a profound difference between the size of these two pistols. First, the G21 has a longer slide. The 21’s barrel length is 4.61 inches compared to 4.02 inches for the G19. The G21’s grip frame is also longer with a total height of 5.51 inches compared to the G19’s 5.01 inches.

There is almost 6 ounces of weight difference with the G21 and G19 weighing in at 29.28 ounces and 23.36 ounces, respectively, with an empty magazine. When loaded, this weight gap grows. The G21 with 13 rounds of .45 ammo weighs in at 38.8 ounces, while the G19 loaded with 15 rounds of 9mm hovers at the 30-ounce mark. That’s over a half a pound of difference and is substantial.

• Performance & Uses: Both of these guns perform admirably, and both can be expected to live up to Glock’s hard-earned and well-deserved reputation for extreme reliability. Both can also be expected to shoot accurately, and share Glock’s well-known manual of arms. The intended use-cases for these pistols differs, however. The Glock 21 was designed as a full-sized, duty pistol. While it can be concealed, this is a little bit outside of its lane. The Glock 19, on the other hand, is designed as a concealed carry pistol. It can be used for duty, but again, this is stretching it's intended purpose. Both the Glock 21 and Glock 19 would serve the Glock owner admirably for home-defense,
• Magazine capacity differences: There is a magazine capacity difference between these two pistols, but it isn’t as great as you might think. The Glock 21 holds 13 rounds, while the Glock 19 holds 15, only two rounds more. There is a hidden advantage to the Glock 19, however: it can use the longer, 17-round magazines intended for the G17, as well as even bigger 19-, 24-, and 33-round magazines. For the Glock 21, 13 round is as good as it gets.
• Considerations for Concealed Carry: There are a few considerations for concealed carry that you should take into account if you are debating between the Glock 21 and the Glock 19. The first is size. As we have seen, the Glock 21 is larger and heavier than the Glock 19, and carrying it for 8, 10, or 12 hours of your day is going to be more taxing than carrying the smaller, lighter 9mm pistol.

The other major consideration is holster support. Most high-quality holster manufacturers make excellent fits for the Glock 19. Relatively very few make good concealment holsters. Also, most magazine pouches are designed for the smaller, standardized 9mm/.40 S&W pattern magazine used by the most popular Glock models including the G17, G19, G22, and G23. A good holster is a huge piece of the concealed carry puzzle, and infinitely more options are available for the Glock 19 than the big Glock 21.

The Best Upgrades for all Glock Models

As we have learned, these pistols were designed with different primary purposes in mind. Both the Glock 21 and the 19 are outstanding performers in their respective roles. Neither is perfect, however. A few modifications can go a long way toward squeezing some extra performance out of these platforms, or any other Glock model.

Aftermarket triggers are an excellent upgrade that can improve the performance of nearly any Glock. Aftermarket, drop-in trigger kits like those offered by Overwatch Precision can decrease the trigger pull length, lighten the trigger, and make it crisper. The flat-faced trigger an also aid in a straight-back pull of the trigger and consistent trigger-finger placement.

Factory Glock sights can sometimes leave a lot to be desired, as well. The Have Blue sights offered by Overwatch Precision offer a rugged, steel rear sight with a clean, crisp, fiber-optic front sight. The aggressive forward angle of the rear sight allows for easy one-handed manipulations, and all the angles are smoothed to be easy on the hands. With the proliferation of red-dot optics the need for taller sights has emerged, and the Have Blue MOS Sight set has got you covered. It’s the same, awesome steel sights (minus the fiber optic) as the standard Have Blue sights, just taller for a co-witness with your optic.

The Glock 21 and Glock 19 are both outstanding platforms. Overwatch Precision offers a host of other upgrades for your favorite Glock model, from the “Original” Glock 17 to the new crop of Slimline Nines, including the Glock 43 and the Glock 48, and the large-frame duty guns like the Glock 20 and 21.