Glock 21 Gen 4 for sale
(9)
GLOCK G21 GEN 4
Brand:
Glock
Action:
Double Action
Barrel Length:
4.61in
Caliber:
.45 ACP
Capacity:
13
Finish Per Color:
Black
(20)
Glock 21 Gen 4 .45 ACP Pistol, Black - UG2150203
Brand:
Glock
Action:
Pistol
Barrel Length:
4.61in
Caliber:
.45 ACP
Capacity:
13+1
Finish Per Color:
Black
(10)
Glock 21 Gen 4 .45 ACP Pistol u2013 PG21502
Brand:
Glock
Action:
Pistol
Barrel Length:
4.61in
Caliber:
.45 ACP
Capacity:
13+1
Finish Per Color:
Matte
(0)
Glock 21 Gen 4 .45 ACP 4.6" Barrel 13-Rounds Rebuilt
Brand:
Glock
Action:
Double Action
Barrel Length:
4.61in
Caliber:
.45 ACP
Capacity:
13
Finish Per Color:
Black
(0)
Glock Glock Glock 21 Gen 4, .45 Acp, 4.61" Barrel, Burnt Bronze Flag, 13-Rd, US Made, Ivs Exclusive UG2150204-BBBWFLAG
Brand:
Glock
Action:
Pistol
Barrel Length:
4.61"
Capacity:
13+1
(0)
Glock G21 Gen4 .45 Auto 4.6 Inch Barrel Black Fixed Sights 10 Round Mag
Brand:
Glock
Action:
Pistol
Barrel Length:
4.61in
Caliber:
.45 ACP
Capacity:
10+1
Finish Per Color:
Black
(0)
GLOCK 21 GEN4 45ACP 13RD 3 MAGS GNS PG2150702
Brand:
Glock
Barrel Length:
4"
Caliber:
.45 ACP
Capacity:
13
(0)
Glock 21 Gen 4 .45 ACP 4.6" 13 Round Pistol, Flat Dark Earth - PG2150203D
Brand:
Glock
Action:
Pistol
Barrel Length:
4.6"
Caliber:
.45 ACP
Capacity:
13+1
(0)
GLOCK 21 FS 45ACP GEN 4 BFG GLOPG2150203BFG
Brand:
Glock
Barrel Length:
4.6"
Caliber:
.45 ACP
Capacity:
13
(0)
Full Conceal M3D Folding Glock 19 GEN4 with 21 Round Magazine - M3DF4
Brand:
Full Conceal
Barrel Length:
4.01"
Caliber:
9×19mm Parabellum
Capacity:
21+1
Finish Per Color:
Black
Marketplace Insights
★ 4.7/5
based on 39 customer reviews across 11 variants from 20 retailers
Customers overwhelmingly praise the Glock 21's reliability, simplicity, and accuracy, with minor concerns about damaged items and misleading product descriptions.
What customers like
Reliability & Performance62%
its one of the most reliable Glock models ever made, it eats any ammo
Simplicity & Ease of Use54%
simple to tear down, clean, and operate
Accuracy & Recoil Management38%
It shoots very much like my G45 9mm
Customer Service & Ordering21%
Easiest process to purchase, it won't be my last gun
Common concerns
Missing Advertised Features5%
PSA advertised that this came with night sights and it didn't
Shipping Damage & QA5%
gun had a damaged front sight, and scratches on the slider
Unclear Fees & Pricing5%
I paid that and had to pay the transfer from FFL as well
Frequently Asked Questions
Glock 21 Gen 4 for sale
Is a Glock 21 Gen 4 a good gun?
The Glock 21 Gen 4 is a reliable full-size .45 ACP pistol with a 13-round capacity, favored by law enforcement and defensive shooters. It's durable, accurate, and widely supported. Retail pricing typically runs $463–$690, averaging around $547.
How much does a G21 cost?
Glock 21 pistols typically cost around $547 based on current marketplace listings. Most retail between $463 and $690 depending on generation and configuration. We track 11 variants across 20 retailers, with 9 currently in stock.
What magazines are compatible with Glock 21 Gen 4?
Glock 21 Gen 4 accepts 13-round .45 ACP factory magazines. Magazines from the Glock 21 and Glock 41 are interchangeable, and Gen 4 and Gen 5 mags are compatible. Aftermarket options from brands like Promag also fit, though compatibility should be verified before purchase.
Why are Glock 21 magazines out of stock?
Factory Glock 21 magazines have faced a known shortage, particularly since the Gen V switch, with extended out-of-stock periods reported across retailers and forums. Our marketplace reflects this — availability is limited. Check our listings for current stock, and consider setting up alerts for restocks.
Will a gen 3 Glock 21 slide fit a gen 4?
Compatibility is disputed. Some sources confirm a Gen 3 Glock 21 slide will fit a Gen 4 frame and function, with a visible gap at the front. However, other sources warn against it, citing different dimensions that may cause the slide to cycle too far rearward. Proceed with caution.
What year did the Glock 21 Gen 4 come out?
Glock released the G21 Gen 4 in 2012. It featured a dual recoil spring assembly, interchangeable backstraps, and improved controls compared to earlier generations.
What is the difference between Glock 21 Gen 4 and 22 Gen 4?
G21 Gen 4 fires .45 ACP with a 13-round magazine; G22 Gen 4 fires .40 S&W with a 15-round magazine. Both are full-size striker-fired pistols sharing the same Gen 4 frame features including interchangeable backstraps. The key differences are caliber, magazine capacity, and slide/barrel dimensions.