What is the Shield Arms Glock 43X / 48 +5 Magazine Extension?
The Shield Arms Glock 43X / 48 +5 Magazine Extension is a precision-machined 6061 aluminum magazine extension that adds 5 rounds of capacity to the new Glock 43X and Glock 48 OEM 15-round magazine - bringing total capacity to 20 rounds. IMPORTANT NOTE: It is compatible with the OEM 15-round magazine only and is not compatible with OEM 10-round magazines or Shield Arms S-Series magazines.
- Compatible with: Glock 43X and Glock 48 OEM 15-round magazines only
- Not compatible with: OEM 10-round magazines or Shield Arms S-Series magazines
- Includes a plus-power replacement spring and all installation hardware
- Backed by Shield Arms' lifetime warranty and Spring for Life guarantee
More Capacity from the Magazine You Already Have
The Glock 43X and Glock 48 OEM 15-round magazine is Glock's newest slim-profile pistol magazines on the market. The Shield Arms +5 Extension takes it further—adding 5 rounds of capacity to bring your total to 20 rounds, with the same reliable feeding you expect from your Glock magazines. CNC-machined from 6061 aluminum with a Type II anodized finish for corrosion resistance and durability, this extension installs without gunsmithing and without permanent modification to your magazines or firearm.
Whether you're running your 43X or 48 in competition, training, duty, or home defense, the Shield Arms +5 Extension gives you a meaningful capacity advantage over the factory configuration—in a package that installs quickly and holds up to hard use. Every extension ships with a plus-power replacement spring to ensure reliable feeding at the increased capacity, and is backed by Shield Arms' lifetime warranty and the Spring for Life guarantee—free replacement springs, forever, no questions asked.
Made in the USA. Covered for life.
Key Features
- +5 Round Capacity Increase: Extends the Glock 43X / 48 OEM 15-round magazine to 20 rounds of total capacity—a meaningful increase for competition stage planning, training efficiency, and duty applications
- 6061 Aluminum Construction: CNC-machined from 6061 aircraft-grade aluminum for a strong, lightweight extension that adds minimal weight and preserves the handling balance of your pistol
- Type II Anodized Finish: Type II anodized for corrosion resistance and long-term durability through years of range use, carry, and training
- Plus-Power Replacement Spring Included: Every extension ships with a plus-power replacement spring engineered to ensure reliable feeding at the increased 20-round capacity—install it with the extension for best performance
- Drop-In Installation: No gunsmithing, no permanent modifications to your magazine or firearm; all necessary hardware included
- Spring for Life Guarantee: Free replacement springs for the life of your extension, forever—learn more
- Lifetime Warranty: Covered by Shield Arms' 100% lifetime warranty against defects in materials and workmanship
- Made in USA: Manufactured in Bigfork, Montana
Compatibility — Read Before Purchasing
Compatible: Glock 43X and Glock 48 OEM 15-round magazines.
Not compatible with OEM 10-round magazines: The Shield Arms +5 Extension is engineered specifically for the OEM 15-round magazine. It will not fit or function correctly with the factory OEM 10-round magazines for the Glock 43X or Glock 48.
Not compatible with Shield Arms S-Series magazines: This extension is not compatible with Shield Arms S-Series magazines. If you are running S-Series magazines in your 43X or 48, this is not the correct extension for your setup.
If you are unsure which magazine you have, check the baseplate of your magazine or contact our team before purchasing.
Capacity Comparison
| Pistol |
Magazine |
Standard Capacity |
With +5 Extension |
Increase |
| Glock 43X |
OEM 15-Round |
15 rounds |
20 rounds |
+5 rounds (33% increase) |
| Glock 48 |
OEM 15-Round |
15 rounds |
20 rounds |
+5 rounds (33% increase) |
Technical Specifications
| Specification |
Details |
| Compatible Pistols |
Glock 43X, Glock 48 |
| Compatible Magazines |
OEM 15-round magazine only |
| Not Compatible With |
OEM 10-round magazines; Shield Arms S-Series magazines |
| Capacity Increase |
+5 rounds (15 → 20 rounds total) |
| Material |
6061 Aircraft-Grade Aluminum |
| Finish |
Type II Anodized |
| Installation |
Drop-in, no permanent modifications |
| Included Hardware |
Plus-power replacement spring, all mounting hardware |
| Warranty |
Lifetime + Spring for Life guarantee |
| Manufacturing |
Made in USA — Bigfork, Montana |
Spring for Life Guarantee
Every Shield Arms magazine extension is backed by our exclusive Spring for Life guarantee. Magazine springs are wear items that lose tension over time with heavy use. Our Spring for Life program means you'll receive free replacement springs for the life of your extension—no questions asked. When you need a replacement, contact us and we'll send one at no charge. Your Shield Arms extension will maintain peak performance for as long as you own it.
Performance Advantages
20 Rounds in a Slim-Profile Package
The Glock 43X and 48 platform was designed around slim, concealable ergonomics—and the OEM 15-round magazine preserves that profile while delivering serious capacity for a single-stack-width pistol. The Shield Arms +5 Extension builds on that foundation, adding 5 more rounds without requiring a different magazine platform or a compromise on the feeding reliability that OEM Glock magazines are known for. At 20 rounds total, your 43X or 48 is running a capacity that rivals full-size pistols—in a significantly slimmer package.
Plus-Power Spring for Reliable Feeding
Increasing magazine capacity without addressing spring tension is how reliability problems start. The Shield Arms +5 Extension ships with a plus-power replacement spring specifically engineered to feed reliably at 20 rounds. Installing the included spring with the extension ensures your magazine cycles consistently from the first round to the last—whether you're in the middle of a competition stage, a training session, or a situation where every round counts.
Competition and Training Efficiency
For USPSA, IDPA, and practical shooting competitors, 20-round capacity in a Glock 43X or 48 platform opens stage planning options that the factory 15-round magazine doesn't. For training, the additional 5 rounds per magazine means fewer reloads per drill and more rounds downrange per session. The aluminum construction keeps the extension light enough that the pistol's balance remains natural in any shooting position.
Frequently Asked Questions
Which magazines is this extension compatible with?
The Shield Arms +5 Extension is compatible with the Glock 43X and Glock 48 OEM 15-round magazine only. It is not compatible with OEM 10-round magazines for either pistol, and it is not compatible with Shield Arms S-Series magazines. If you are unsure which magazine you have, check the baseplate or contact our team before ordering.
Will this work with my Shield Arms S-Series magazines?
No. This extension is not compatible with Shield Arms S-Series magazines. It is engineered specifically for the Glock OEM 15-round magazine for the 43X and 48.
Will this work with my OEM 10-round magazine?
No. This extension is designed for the OEM 15-round magazine only and will not fit or function correctly with the OEM 10-round magazine for the Glock 43X or Glock 48.
What is included in the package?
Each Shield Arms +5 Extension includes the aluminum extension body, a plus-power replacement spring, all necessary mounting hardware, and installation instructions.
Why is a replacement spring included?
Increasing magazine capacity requires additional spring tension to feed reliably at the new round count. The included plus-power replacement spring is engineered specifically for the 20-round configuration. We recommend installing it with the extension for consistent, reliable feeding from top to bottom.
Does installation require any permanent modifications?
No. The extension uses a drop-in design. Installation requires no gunsmithing and no permanent modification to your magazine or firearm. All necessary hardware is included.
Will this extension affect reliability?
No—when installed with the included plus-power replacement spring, the Shield Arms +5 Extension is engineered to maintain the feeding reliability of your OEM Glock 15-round magazine. The plus-power spring is a required part of the installation for reliable function at 20 rounds.
Will this affect concealability?
The extension adds length to the magazine and will extend below the grip of the pistol depending on your carry configuration. The extension is particularly well-suited for a spare mag, competition, training, duty, and home defense applications where maximum capacity is the priority.
Is this extension legal in my state?
Magazine capacity restrictions vary by state and locality. The +5 Extension brings total capacity to 20 rounds, which exceeds legal limits in some jurisdictions. Check your applicable local and state laws before purchasing. Shield Arms cannot ship to restricted locations.
What is the Spring for Life guarantee?
The Spring for Life guarantee means Shield Arms will provide free replacement springs for the life of your extension—no questions asked. Magazine springs are wear items that lose tension over time with heavy use. When you need a new spring, contact us and we'll send one at no charge.
What warranty is included?
The Shield Arms +5 Extension is covered by our 100% lifetime warranty against defects in materials and workmanship, plus the Spring for Life guarantee for free replacement springs for the life of the product.
Is this extension made in the USA?
Yes. The Shield Arms Glock 43X / 48 +5 Extension is manufactured in Bigfork, Montana, using American materials and precision CNC machining.
Is this extension compatible with Shield Arms magwells?
Yes. The Shield Arms Glock 43X / 48 +5 Extension is compatible with both our carry and premium magwell.
Who Should Buy the Glock 43X / 48 +5 Extension
- Glock 43X and 48 Owners Running OEM 15-Round Magazines: Anyone looking to get more rounds out of the magazine they're already carrying—5 more rounds with no magazine swap required
- Competitive Shooters: USPSA, IDPA, and practical shooting competitors who want 20-round capacity in the slim 43X/48 platform for improved stage flexibility
- Duty and Law Enforcement: Officers carrying the 43X or 48 who want increased capacity in their duty or backup magazines without changing pistol platforms
- Home Defense Users: Anyone who wants maximum capacity from their 43X or 48 in a home defense configuration where concealability is less of a concern
- High-Volume Trainers: Shooters who want fewer reloads per drill and more rounds downrange per magazine during live-fire training sessions
Made in Montana. Backed for Life.
Shield Arms manufactures every product at our facility in Bigfork, Montana, to the standard that competitive shooters, law enforcement professionals, and serious civilian shooters have trusted since day one. The Glock 43X / 48 +5 Extension is backed by our 100% lifetime warranty against defects in materials and workmanship and the Spring for Life guarantee—free replacement springs forever. More capacity. More reliability. Made in the USA.
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