What does a Glock 21 magazine extension do?

It increases your Glock 21’s ammunition capacity. Extensions can add anywhere from 2 to 17 additional rounds depending on the model, giving you more firepower without changing magazines.

Do I need a stronger spring with a mag extension?

Yes, especially with extensions that add more than 2 rounds. Reputable brands like Henning Group include upgraded springs to ensure proper feeding and reliability.

Will this fit the Glock 41 or Glock 30?

These extensions are compatible with Glock 41 (full-size .45 ACP), but not recommended for Glock 30 due to differences in grip length and magazine design.

Are magazine extensions legal in my state?

Magazine capacity laws vary by state. Some locations restrict the use of extensions that bring mags over 10 rounds. Check your local regulations before purchase.

Glock 21 Magazine Extension | +2 to +5 Round Extensions

**Henning Group Blueline Magazine Extension and Spring for Glock 21 / 41 - 45 ACP** $39.95

**Kriss Magex2 Kit For G21 +17rd 3pk** $85.99

**Kriss Ex2 Kit For G21 +17rd 45acp Bk** $41.50

**Kriss Magex2 Kit For G21 +17rd 45acp** $41.50

Glock 21 Magazine Extension – More Rounds. More Control. More Confidence.

Upgrade your Glock 21 with a precision-engineered magazine extension built for more firepower, better control, and enhanced tactical readiness. Whether you're a competitive shooter, law enforcement officer, or an everyday carry enthusiast, these mag extensions give your .45 ACP powerhouse the edge it deserves.

At Mounts Plus, we stock only battle-proven, reliable Glock 21 magazine extensions from brands like Henning Group and Kriss, offering a perfect fit and flawless function.

Why Choose a Glock 21 Magazine Extension?

➕ Increased Capacity – Add up to +5 rounds depending on the extension
🧠 Improved Ergonomics – Get a better grip and quicker mag changes
🔒 Reliable Feeding – Designed to function under pressure with proper spring tension
🔧 Easy Installation – Install in minutes, no gunsmith required
🛡️ Built for Duty & Defense – Trusted by tactical shooters and professionals

Available Glock 21 Magazine Extensions

Product	Capacity	Material	Notes
Henning Group Blueline Extension	+2 to +5	Aluminum	Includes power spring, USA-made
Kriss MagEx2 Kit (G21)	17	Polymer/Metal	Extends to 30+ rounds, .45 ACP
Kriss MagEx2 3-Packs	17	Polymer	Ideal for competition or prep kits

SOURCE: Sources

💡 All extensions fit Glock 21, Glock 41, and .45 ACP variants using standard Glock mags.

💬 FAQs – Glock 21 Magazine Extensions

Q: How many rounds does a Glock 21 hold with an extension?
A: The standard Glock 21 holds 13 rounds. With an extension, you can hold 15–17+ rounds, depending on the brand and model.

Q: Are these extensions legal in my state?
A: Most states allow magazine extensions, but some restrict total magazine capacity. Always check your local laws before installing.

Q: Do I need a new spring for my extension?
A: Some extensions include upgraded springs (like Henning Group). It's highly recommended to use the supplied spring to ensure reliable feeding.

Q: Will these work with Glock 41 or Glock 30?
A: Yes for Glock 41 (same full-size mag). Not recommended for Glock 30 due to grip size compatibility.

🚀 Why Mounts Plus?

✅ Factory-Authorized Glock Accessory Dealer
🚚 Fast, Secure Shipping from Florida
🧠 Expert Support — Real Shooters, Real Answers
🔐 100% Secure Checkout

🛒 Get More Out of Your Glock 21

Whether you're on duty, on the range, or just upgrading your EDC rig, a Glock 21 magazine extension is one of the smartest upgrades you can make. More rounds. Better control. Proven reliability.

👉 Order your Glock 21 mag extension today — in stock & ready to ship at Mounts Plus.

Glock 21 Magazine Extension | +2 to +5 Round Extensions | Mounts Plus