Kriss USA Mag-Ex2 Extension Kit for Glock 21 Gen3-5, Polymer, Black Finish, Adds 17 Rounds, 45 ACP, 30rd Total
$29.69
$32.99
(You save
$3.30
)
- Capacity-Rounds:
- 30
- Type:
- Accessory
- Firearm Group:
- Handgun
- Firearm Make Fit:
- Glock
- Caliber-Gauge:
- 45 ACP
- Finish-Color:
- Black
- Model:
- Mag-Ex2
- Material:
- Polymer
The Kriss USA Mag-Ex2 Extension Kit is a capacity-boosting solution for Glock 21 Gen3 through Gen5 shooters who want more rounds on tap without swapping guns. This polymer extension system works with factory Glock 21 magazines to push your .45 ACP capacity to 30 rounds—a meaningful increase for tactical training, competition, or self-defense practice where more ammunition between reloads matters. The reinforced composite construction keeps weight down while the black finish matches your pistol's aesthetics, whether you're running a stock Glock or a carbine platform that accepts Glock mags.
Installation is straightforward: the Mag-Ex2 kit includes an extended baseplate and reinforced spring that marry with your existing factory Glock 21 magazine body and follower. No gunsmithing required. The polymer design balances durability with reliability, so you're not sacrificing feeding consistency for capacity. It's a proven upgrade for Glock pistol owners and anyone running a .45 ACP PCC (pistol caliber carbine) that uses Glock mags.
One practical note: loading 30 rounds of .45 ACP into an extended magazine will require progressively more hand pressure as the spring compresses. Many shooters find a magazine loader—like the UpLULA—makes the job significantly easier and faster, especially during high-round-count sessions. It's a small quality-of-life consideration that pays dividends on the range or at a match.
Key Features
- Raises Glock 21 magazine capacity to 30 rounds of .45 ACP (adds 17 rounds to factory 13-round mag)
- Made from durable reinforced polymer for lightweight, corrosion-resistant construction
- Black finish complements Glock pistols and .45 ACP carbines
- Works with factory Glock 21 magazine bodies and followers—no permanent modifications
- Extended spring and baseplate design maintains reliable feeding
Specifications
| Brand | Kriss USA |
| Product Type | Magazine Extension Kit |
| Caliber | .45 ACP |
| Compatible Firearm | Glock 21 Gen3, Gen4, Gen5 |
| Material | Reinforced Polymer (Baseplate & Spring) |
| Finish | Black |
| Total Capacity | 30 rounds |
| Capacity Increase | 17 rounds (from factory 13-round mag) |
| Also Compatible With | Glock magazine-compatible .45 ACP carbines |
Frequently Asked Questions
Will the Mag-Ex2 kit work with my Glock 21 Gen3, Gen4, or Gen5?
Yes. The Mag-Ex2 extension kit is designed specifically for Glock 21 magazines across Gen3, Gen4, and Gen5 platforms. It works with factory Glock 21 magazine bodies, so compatibility is straightforward.
Can I use this extension kit with my .45 ACP pistol caliber carbine?
Yes, as long as your carbine accepts standard Glock 21 magazines. The Mag-Ex2 is compatible with Glock magazine-fed .45 ACP carbines, making it a useful upgrade for higher round count between reloads during training or matches.
What's included in the kit?
The Mag-Ex2 kit includes an extended baseplate outer sleeve and an extended spring, both made of reinforced polymer. You supply your own factory Glock 21 magazine body and follower; no additional hardware is needed.
Is hand-loading difficult with a 30-round magazine?
As you approach full capacity, spring tension increases and manual loading becomes progressively harder. Many shooters use a magazine loader, such as the UpLULA, to make loading faster and easier—especially during high-volume practice sessions.
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