Handguns > Semi-Auto

The GLOCK Gen4 G21 .45 ACP Pistol

This tough, reliable full-size .45 is now available with GLOCK’s latest upgrades.


It was about seven years ago that a Gen3 G21 joined my shooting set. I had been working with GLOCKs chambered in 9 mm and 40 S&W for a while and I was ready for a model chambered in .45 ACP. Fortunately, I was on site at a local law enforcement supply and firearms store when this particular pistol was put on display.

My G21 spent a year traveling around the country as a marketing sample. Regularly handled, but never shot, the pistol was pristine. Because it was technically a used gun, the G21 had a discounted price tag attached that could have read, "Take Me Now!" instead of a dollar amount.

In the years since this purchase, the G21 has become one my favorite .45s to shoot. Although the pistol is rather large for concealed carry, the G21 has filled all of the shooting jobs I've given it with aplomb. With the success of the Gen4 GLOCK pistols released so far, GLOCK decided to make 2012 the year the G21 is released with the latest features available.

Pistol Features
The dimensions of the Gen4 G21 .45 ACP make it a duty-size pistol, but the polymer frame reduces the unloaded weight to a reasonable 26.46 ounces. The slide is made of gas nitrate treated steel and the 4.61-inch barrel contains octagonal rifling. The Gen3 single recoil spring, supported by a polymer guide rod, has been replaced by a dual recoil spring assembly with steel supports in key locations. This new assembly promises to be durable while reducing felt recoil more effectively than the previous arrangement. This G21 arrived with GLOCK MH3 steel night sights installed, but polymer standard sights are also available.

The trigger is fitted with a 5.5-pound trigger connector, which is a GLOCK standard. Reduced trigger weight connectors are available if you want to lighten the pull. GLOCK pistols feature three independent passive safeties that sequentially disengage as the trigger is pressed. These include the trigger safety, firing pin safety and drop safety. These pistols do not have magazine safeties, meaning, the pistol will fire if the magazine is removed and a live round is in the chamber.

Another of the Gen4 features is an enlarged and reversible magazine release. This new release is a boon for shorter-fingered shooters. The wider, longer textured surface of the release, combined with the slightly reduced frame size, eliminates the need to shift the shooting hand grip in order to reach it. The polymer frame features a molded-in Picatinny compatible accessory rail. Because this is a full-size frame, the rail will accept a wide range of light and laser modules. The Gen3 pistols introduced finger grooves to the grip, and the finger grooves are still present on the Gen4 model. Not everyone wants the finger grooves, but it's a love 'em or leave 'em feature of the pistol.

The frame contains internal steel contact points to prevent undo wear and to ensure reliable function. The previous frame featured a light irregular texture on the sides with patterns of lines and squares on the back strap, finger groves and the finger rest incorporated into the trigger guard. The Gen4 has what is called a Rough Texture Frame. Small, raised, blunted pyramids cover all four sides of the grip, and raised serrations are molded into the trigger guard finger rest. This new texture is more aggressive, but it's still comfortable to shoot with bare hands.

One more change to the frame is the addition of interchangeable backstraps. Two straps and an installation tool are provided. The frame with no backstrap installed is the smallest grip size available with this model. The bare frame provides a .08-inch reduction in the distance to the trigger compared to the Gen3 frame. The installation of the small backstrap brings the frame back to the original size, and the installation of the larger back strap adds an extra .08 inches for shooters with larger hands.

At the Range
On the range, the G21 behaved just as a GLOCK is expected to, but notably better than its predecessor in certain respects. The slide cycles more smoothly on the Gen4. The reduction in recoil and muzzle flip provided by the new dual-spring recoil assembly are noticeable and welcome. The slightly smaller grip, the more aggressive grip texture and extended magazine release all worked together to make running the G21 a more comfortable and positive process.

In regard to reliability, the G21 digested a variety of ammunition with no malfunctions. This included bulk practice-grade ammo, imported steel case loads, defensive hollow points in a variety of bullet weights and hot +P rounds. The formal accuracy testing for the G21 was conducted using five consecutive, five-shot groups fired from a bench rest into targets set at 25 yards. The best single five-shot group of 2.75 inches was produced by ASYM 185-grain +P Barnes TAC-XP hollow points. The ASYM load also produced the best average of 3.05 inches. DoubleTap 230-grain brass jacketed hollow points averaged 3.15 inches, followed by Winchester 230-grain PDX1 bonded hollow points with an average of 3.3 inches.

Taking advantage of the G21's accessory rail, the range time was also used to test drive the new Gen 2 Viridian X5L green laser and light module. The 154 lumen taclight is bright and powerful. The green laser dot was clearly visible on targets at every test distance, including the 25-yard mark. The variety of programmable light and laser modes are easy to cycle through by pressing both activation switches at the same time. Lightweight and compact for all the power and features it has to offer, the X5L is an ideal accessory for the G21 or any full-size defensive pistol.

Final Thoughts
GLOCK's motto, like its pistols, is simple: Perfection. Although this statement is argued by those who disagree, GLOCK has a good deal to be proud of in its products. In fact, if the old saying is true that imitation is the sincerest form of flattery, then GLOCK should be positively blushing. Pistol manufacturers around the world have been and are still busily striving to imitate and implement the design principles that have made the GLOCK such a popular choice for over 25 years. While there is certainly nothing wrong with the Gen3 G21, the changes implemented in the Gen4 version of this full-size .45 ACP pistol can be accurately labeled improvements upon perfection.

Manufacturer: GLOCK; glock.com
Model: G21
Action: Safe Action
Caliber: .45 ACP
Finish: Gas Nitrate
Grips: Multiple Backstrap System
Sights: Standard or Night Sights
Barrel Length:
Overall Length: 8.23”
Height: 5.47”
Width: 1.28”
Weight: 26.46 ozs., Unloaded
Capacity: 13+1 Rounds
Twist: 1:15.75” RH
Rifling: Octagonal 
Accessories: Hard Case, Two Magazines & Speed Loader, Two Backstraps with installation tool, Cleaning Set
Suggested Retail Price: $687 Standard Sights, $734 Night Sights

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26 Responses to The GLOCK Gen4 G21 .45 ACP Pistol

Mike g wrote:
December 21, 2014

Just got my g21gen 4 . My son has one as his service weapon and he let me shoot it at range . I am very pleased with my new one can't wait to shoot it .

Homer VanNousone wrote:
December 09, 2014

I just bought my first glock today from the pawnshop for $419.its glock 21 gen 3 with two mags.the gun looks brand and in perfect condition.i feel very lucky today

PK Costner wrote:
April 14, 2014

I have been a 1911 guy for most of my life. Never liked the Glocks till now. I had a 1911 complete failure and bought a G21 gen 4. I absolutely LOVE it! The improvements Glock has made are better than perfect. I love the improved trigger, frame dimensions, recoil springs and so much more. I convert! Now I am a Glock true believer!

AL D. wrote:
June 16, 2013

I purchased the g34 9mm a month ago and took it to the range. I fired 50 rounds flawlessly. It was such a joy to shoot. The g34 shot very accuratly at 21',35', and 50'. I was very happy with the groups. At 21' grouped 4 inches, at 35' grouped 5', at 50' 7 inches. They could be tighter, but it wasn't the guns fault. I shot free handed, not on a rest position, and it was my first time shooting this gun. I am now looking to buy the g21 g4 and hope it will be as much fun to shoot and be as accurate as the g34. I will continue to work on my skills as a shooter so the g34 and g21 can perform tighter groups as I get better. Now I know why so many people love their Glocks, I now I do...

ken mc cune wrote:
March 06, 2013

i have a glock model 21 45acp no rail do you have alaser sight for the gun

0 brass in face problems with 3 heavily used Gen 4 Glocks wrote:
February 26, 2013

Not a single one has thrown brass in my face. In fact 2 different Gen 3 Glocks I have owned have been the only Glocks that have done it. I guess it was the gen 3 that went the way of the dodo if we are going to go off of such unscientific and incomplete data to draw a conclusion. Also, those 2 gen 3 Glocks were corrected in all of 10 minutes to make them stop throwing brass straight back. What a ridiculous reason to avoid a gen 4.

+ wrote:
January 13, 2013

I have had my Gen 4 for about six months now. Probably ran about 3,000 rounds or so through it. Man, i just love it. Anyway, regarding getting slapped in the face with a piece of hot ejected brass. hmmmm... seems to me that you would have to be a complete idiot who shoots with the pistol right next to your face LOL. Does anyone else really have that problem ?

Bruce Norden wrote:
October 30, 2012

I have previously owned two glock 19 's gen 3 9mm. Never any issues. I just purchased a new gen 4 19 9 mm made in the USA and have put approximately 300 rounds thru it. No issues

J. Umerlik wrote:
October 14, 2012

I agree that Glock is a superb handgun, but there is a lot of excellent handgun's out there. S&W,Wilson Combat,HK,Sig Sauer,Rock River Arms,Kimber,etc. What counts is the way it feels in your hands. I think people just want too say "I own a Glock" Like I said; Glock is a superb handgun but is probably the ugliest gun on the market. That's my opine!! Easy on the emails please.

Curious wrote:
September 07, 2012

@AR-George: How exactly do you carry a Glock "cocked and locked"???

Steve wrote:
August 21, 2012

I shoot Glock exclusively! Own 17, 19, 21, 23, and 36. Got my sights on a 20 & 35. All these weapons are exceptional! No issues at all! The Glock series of weapons are proven for duty, off-duty and concealed use. No better weapon system around in any caliber. I stake my life on it every day!

Mike Ollie Sr wrote:
August 21, 2012

I have a Glock22 .40 cal and had the trigger lightened up and I would swear by this gun I love it and I have never had a misfire, jam or any other problems with it and I would reccommend it to anyone who is looking for a gun, this is also my ccw weapon, it is a big for ccw but to me if people see it they would possibly behave themselves, lol.

Dep wrote:
July 31, 2012

Considring all the complaints about brass-to-the face and ejection problems with the Gen 4 guns, I made sure I purchased a Gen 3 26 for my wife. Glock Perfection has gone the way of the do-do.

Plujak wrote:
July 21, 2012

My G4 21 is the first Glock I've owned. I have Berettas -- a .380 and a 9mm 92FS. I love the 92. I've shot a few hundred rds thru the 21 and am still trying to get better with it than the 92FS. Can't do it. Got close patterns with the 92FS and am all over the place with the 21...but I'm still all in the black. And the most important part is that I LOVE my .45. I figure if I can keep 'em in the black I can stop someone coming through my front door.

Loy wrote:
January 31, 2012

I have a Gen2 MODEL 21 that I have run 30000 rds through since new. 98% hand loads and I have never had a bulged case, jammed round or out of battery fire. Like a Timex, It takes a lickin' and keeps on tickin'.

Gary wrote:
January 24, 2012

Glocks are famous for having digested zillions of rounds in tests over the years and surviving. That said, a Google of the Internet will reveal lots of documented cases, including many from Law Enforcement agencies, where the Glock design caused major malfunctions and over-pressure factory and handloaded ammo caused KBs. So the problem is that both factory ammo and handloads can cause a KB. Luckily, most of us have the expertise to produce safe ammo, probably even safer than factory stuff which is subject to numerous recalls. But the real problem with reloading for a Glock is the bulge produced by the unsupported chamber. Here is what Bryce Towsley had to say in Gun Digest: http://www.gundigest.com/reloading-handloading-articles-advice/shooting_fixglockbulge

Ted wrote:
January 24, 2012

My Gen 4 model 19 has 8400 rounds though it and one FTF. Glock supplied the replacement spring at 7100. Still perfect. My Gen 4 26 is my CCW has had zero problems. My Kimber has had issues, sadly.

jay wrote:
January 23, 2012

i have bought 2 fourth gen glocks they both jammed on me i think there junk so i went back to the ole model gen 3 if it aint broke dont fix it .the 4 th gen i had to replace the spring 2 times that junk still jammed i would not recommend that crap to ne one that can get some one killed in a fire fight

Sorzy wrote:
January 23, 2012

@ Gary, all guns suggest NOT to use reloads and most will void your warranty if something happens and it's found you were using reloads. That said, the KB's you speak of, as rare as they are for as many GLOCKS there are in the market and in use, as you noted were caused from reloads. I have never heard of a KB in a GLOCK caused from using factory loads. But if you want to shoot reloads, just get a Storm Lake or Lone Wolf barrel. I know, I know, you shouldn't have to buy another barrel just to shoot reloads. Well, according to the manufacture, GLOCK, again, you're not suppose to use reloads in them in the first place anyhow. Read the owners manual for most any semi-auto. It'll say something like..Reloads not recommended or Warranty void if handloads used. And where are these too many KB's? And how many is too many for ALL the GLOCKS out there? I've seen only 1 maybe 2 KB's. And every time someone says there's another, it's the same 1 or 2 as before; just worded differently on a different website with the same pictures. Just buy a G20 and don't look back. Just don't use reloads. But if you want to, just get a barrel and shoot away. Otherwise spend even more money and buy the Colt Elite 10mm. @ Tom, me too. The G21 Gen. 4 I just searched on Gun Gallery using their Gun Genie showed it came with 3 mags., so? But then for some reason, I like the Gen. 3's. Not thrilled with the grip stippling and have big enough hands I'm good as it is without needing to use the grip inserts. So I figure why pay extra. I mean, as mentioned in the article, there's nothing wrong with the Gen. 3's. And if you ask me, the "improvements" of/in the Gen. 4 are a matter of opinion.

R BURNETT wrote:
January 23, 2012


Gary wrote:
January 23, 2012

Here is the site with the most information on what causes KBs, including firing out of battery: http://www.thegunzone.com/glock/glock-kb-faq.html

Dave wrote:
January 23, 2012

Take a look and see what LAPD has to say about the glock 21 .

AR-George wrote:
January 23, 2012

I have had more than 15 Glocks and carry cocked and locked, compared to other handguns I find the Glock to be the safest to carry in this manner. I just picked up a new G22 and love it! I would dispute an earlier comment regarding a problem with them firing out of battery, after shooting thousands of rounds, it has NEVER happened! Keep up the good work Glock!

Tom wrote:
January 23, 2012

I thought all Gen4's came with 3 magazines?

Gary wrote:
January 21, 2012

With their over-size chambers and extra-deep feed ramps, Glocks are the perfect choice for law enforcement where reliability is of prime importance. But I wish AR, or any magazine, would put the advertising dollars aside and address the KB factor that is brought on by handloaders trying to live with the unsupported chamber and Glocks's habit of occasionally firing out of battery. I would really like to get a Model 20 in 10mm but I have seen and read about too many KBs to feel safe buying one.

Glock 20 lover wrote:
January 20, 2012

The Glock 20 and 21 use the same frames. Now the the frame has been made, the G20 generation 4 can't be far behind.