Quick Answer: What is the S15 +5 Magazine Extension?
The Shield Arms S15 +5 Magazine Extension is a precision-machined aluminum baseplate extension that adds 5 additional rounds to your S15 Magazine, increasing total capacity from 15 to 20 rounds. When combined with the S15 magazine platform, this gives your Glock 43X or 48 a total capacity of 20+1 rounds—more than doubling the factory 10-round capacity and matching full-size pistol capacity in a micro-compact frame.
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Maximum Capacity for Serious Applications
The S15 +5 Magazine Extension represents the ultimate capacity solution for Glock 43X and 48 owners who prioritize maximum ammunition availability. While factory Glock magazines limit you to just 10 rounds, this extension—when paired with the Shield Arms S15 Magazine—delivers an impressive 20+1 round capacity that rivals full-size service pistols. This transformative upgrade makes the compact Glock 43X/48 platform viable for competitive shooting, home defense scenarios, and extended range sessions where capacity and reduced reload frequency are critical advantages.
Engineered from aerospace-grade 6061 billet aluminum and finished with durable Type-2 anodizing, the S15 +5 Extension combines maximum capacity with professional-grade construction. The design includes ergonomic index cuts for positive magazine extraction, an innovative easy-access floor plate that permits complete magazine maintenance without extension removal, and full compatibility with Shield Arms magwells and most aftermarket flared magazine wells. Each extension includes a specially engineered 12-coil power spring calibrated specifically for reliable feeding with the substantially increased 20-round capacity.
Whether you're a competitive shooter in USPSA Carry Optics division seeking every possible advantage, a homeowner who demands maximum defensive capacity, or a serious training enthusiast who wants to maximize trigger time between reloads, the S15 +5 Magazine Extension delivers full-size pistol capacity in your micro-compact carry gun. Backed by Shield Arms' reputation for innovation and American manufacturing excellence, this extension transforms your Glock 43X or 48 into a true multi-role platform.
Key Features
- +5 Round Capacity: Increases S15 magazine capacity from 15 to 20 rounds for a total of 20+1 in your Glock 43X/48—matching full-size pistol capacity
- Premium Construction: CNC-machined from billet 6061 aluminum for exceptional strength while maintaining a lightweight profile
- Type-2 Anodized Finish: Available in multiple color options including black, FDE, grey, OD green, and mud for customization and superior corrosion resistance
- Easy-Access Floor Plate: Unique design allows complete magazine servicing and cleaning without removing the extension, simplifying maintenance
- Ergonomic Index Cuts: Precision-machined cuts on extension body provide positive grip and purchase when extracting magazines from pouches or during tactical reloads
- 12-Coil Power Spring: Included upgraded spring is specifically engineered for reliable feeding and optimal performance with 20-round capacity
- Universal Magwell Compatibility: Works seamlessly with Shield Arms Carry Magwell, Shield Arms Premium Magwell, and most aftermarket flared magazine wells
- Made in USA: Proudly designed, engineered, and manufactured in the United States with precision CNC machining
Important: Required Components
The S15 +5 Magazine Extension is designed exclusively for use with Shield Arms S15 Magazines. It will not function with factory Glock magazines. For optimal performance and reliability, Shield Arms strongly recommends using either the Premium S-Series Steel Mag Catch or Standard S-Series Mag Catch with your S15 magazine system.
Color Note: In 2025, the anodized shade of the 'Mud' color option was updated. Items previously purchased in Mud may not match the current shade exactly.
Technical Specifications
| Specification |
Details |
| Compatible Firearms |
Glock 43X, Glock 48 |
| Compatible Magazines |
Shield Arms S15 Magazine |
| Capacity Increase |
+5 rounds (15 to 20 total magazine capacity) |
| Material |
6061 Billet Aluminum |
| Finish |
Type-2 Anodized |
| Color Options |
Black, FDE, Grey, OD Green, Mud |
| Included Components |
Extension body, 12-coil power spring |
| Magwell Compatibility |
Shield Arms Carry Magwell, Shield Arms Premium Magwell, most aftermarket flared magwells |
| Manufacturing |
Made in USA |
| Warranty |
Lifetime warranty against manufacturing defects |
Capacity Comparison
| Magazine Configuration |
Magazine Capacity |
Total Capacity (w/ +1) |
Increase vs. Factory |
| Factory Glock 43X/48 Magazine |
10 rounds |
10+1 |
Baseline |
| Shield Arms S15 Magazine |
15 rounds |
15+1 |
+5 rounds |
| S15 Magazine + S15 +2 Extension |
17 rounds |
17+1 |
+7 rounds |
| S15 Magazine + S15 +5 Extension |
20 rounds |
20+1 |
+10 rounds (100% increase) |
Frequently Asked Questions
Will the S15 +5 Extension work with factory Glock magazines?
No, the S15 +5 Magazine Extension is engineered specifically for Shield Arms S15 Magazines and will not fit or function with factory Glock magazines. The S15 magazine uses a unique double-stack metal design with dimensions that differ significantly from OEM Glock magazines, requiring a purpose-built extension.
How much length does the +5 extension add to my pistol?
The S15 +5 Extension adds approximately 1.2 inches to the overall length of your magazine and pistol. While this provides substantial additional capacity, the extension does protrude noticeably beyond the grip frame. This makes the +5 extension ideal for home defense, competition, and range use where maximum capacity outweighs concealability considerations.
How does the +5 extension compare to the +2 extension for concealed carry?
The S15 +2 Extension adds only 0.5 inches and 2 rounds, making it better suited for everyday concealed carry where discretion is paramount. The +5 extension adds 1.2 inches and 5 rounds, prioritizing maximum capacity over concealability. Many users choose both: +2 extensions for carry magazines and +5 extensions for backup, home defense, or range magazines.
Is the S15 +5 Extension suitable for competition shooting?
Absolutely. The S15 +5 Extension is extremely popular in USPSA Carry Optics division and other competitive shooting disciplines. The 20+1 round capacity reduces reload frequency during stages, while the index cuts facilitate faster magazine extraction during tactical and emergency reloads. Many competitive shooters consider the S15 +5 system essential equipment for maximizing stage performance.
Do I need to purchase a magazine catch to use the S15 magazine system?
Shield Arms strongly recommends replacing the factory polymer magazine catch with either the Premium S-Series Steel Mag Catch or Standard S-Series Mag Catch. The steel mag catch is specifically designed to work with the S15's metal magazine body and provides superior durability and reliability compared to the factory polymer catch.
Can I service my magazine without removing the extension?
Yes, one of the key innovations of the S15 +5 Extension is its easy-access floor plate design that allows complete magazine disassembly, cleaning, and servicing without removing the extension from the magazine body. This design feature significantly simplifies routine maintenance and ensures you can keep your magazines in optimal operating condition with minimal effort.
What is the Spring for Life guarantee?
Shield Arms' Spring for Life guarantee ensures that if your magazine spring wears out at any point during the life of your S15 magazine or extension, Shield Arms will replace it completely free of charge. This lifetime spring replacement guarantee demonstrates our commitment to long-term reliability, customer satisfaction, and standing behind our products indefinitely.
Is the S15 +5 Extension compatible with magwells?
Yes, the S15 +5 Extension is fully compatible with the Shield Arms Carry Magwell, Shield Arms Premium Magwell, and most aftermarket flared magazine wells designed for the Glock 43X/48 platform. The magwell-extension combination is particularly popular among competitive shooters for faster, more consistent reloads. Always verify fitment with your specific magwell manufacturer.
Does the additional capacity affect reliability?
No, the S15 +5 Extension is designed to maintain the exceptional reliability of the S15 magazine system. Each extension includes a precision-engineered 12-coil power spring specifically calibrated for the 20-round capacity. When properly installed, maintained, and used with quality ammunition, the S15 +5 Extension provides reliable feeding and function that meets or exceeds factory specifications.
Is the S15 +5 Extension legal in all states?
Magazine capacity laws vary significantly by state, county, and municipality. Some jurisdictions have restrictions that limit magazine capacity to 10, 15, or other round counts, which may prohibit the use of 20-round magazines. It is exclusively the buyer's responsibility to know and comply with all federal, state, and local laws regarding magazine capacity in their area. Shield Arms does not provide legal advice—consult with a qualified attorney or local law enforcement if you have questions about legality in your jurisdiction.
What colors are available for the S15 +5 Extension?
The S15 +5 Extension is available in multiple Type-2 anodized color options including Black, Flat Dark Earth (FDE), Grey, OD Green, and Mud. This variety allows you to match your firearm's finish or create a custom aesthetic. Note that in 2025, the Mud color shade was slightly updated, and older Mud-colored items may not perfectly match newer production runs.
Can I purchase magazines with the +5 extension already installed?
Yes, Shield Arms offers S15 magazines with the +5 extension pre-installed for maximum convenience. This factory-installed option ensures proper assembly, eliminates installation concerns, and allows you to start using your 20-round extended-capacity magazines immediately upon delivery. This is particularly popular among competitive shooters and those new to magazine extension installation.
Who Should Buy the S15 +5 Magazine Extension?
- Competitive Shooters: USPSA Carry Optics, IDPA, and other competition shooters who need maximum capacity and reduced reload frequency during timed stages
- Home Defense Users: Homeowners and apartment dwellers who rely on their Glock 43X/48 for personal protection and want maximum ammunition availability without compromising platform size
- Range Enthusiasts: Shooters who want to maximize trigger time and minimize reload interruptions during training sessions and recreational range visits
- Law Enforcement Officers: Off-duty or backup gun applications where maximum capacity in a compact platform provides tactical advantages
- Firearms Instructors: Training professionals who want to demonstrate techniques with fewer interruptions and students who want extended shooting strings between reloads
- Serious Glock 43X/48 Owners: Enthusiasts who have invested in the platform and want to maximize its capability for non-concealed-carry applications
- Multi-Purpose Gun Owners: Those who use their Glock 43X/48 for multiple roles and want different capacity options for different scenarios (carry, home, range, competition)
- Backup Magazine Users: Concealed carriers who use compact +2 magazines for carry but want maximum-capacity +5 magazines as backup or vehicle guns
Installation & Setup
Installing the S15 +5 Magazine Extension is straightforward and can be completed in minutes with basic tools and mechanical aptitude. The extension comes with comprehensive instructions and involves disassembling your S15 magazine, replacing the factory baseplate and spring with the +5 extension components and included 12-coil power spring, and reassembling the magazine. For visual installation guidance, detailed step-by-step instructions, and video tutorials, visit our Installation Guides page. If you prefer a ready-to-use solution or want to ensure factory-perfect installation, consider purchasing S15 magazines with the +5 extension already installed.
Related Products & Accessories
- Shield Arms S15 Magazine - Required for use with this extension. The revolutionary 15-round double-stack metal magazine that serves as the foundation for the entire high-capacity S15 system and transforms the Glock 43X/48 platform.
- Premium S-Series Steel Mag Catch - Highly recommended for optimal S15 magazine performance and reliability. Precision-machined from steel to provide superior durability and proper engagement with S15 metal magazines compared to factory polymer magazine catches.
- Standard S-Series Mag Catch - A cost-effective steel mag catch option that provides reliable function with S15 magazines at a more accessible price point than the Premium version while maintaining quality performance.
- S15 +2 Magazine Extension - For those who want increased capacity with better concealability. Adds only 2 rounds and minimal length, making it ideal for everyday carry magazines while the +5 serves for backup, home defense, or competition use.
- Shield Arms Carry Magwell - Dramatically improves reload speed and magazine insertion consistency. Particularly valuable for competitive shooters using the S15 +5 extension who need every advantage during timed stages and tactical reloads.
American Quality, Lifetime Confidence
Every Shield Arms S15 +5 Magazine Extension is proudly designed, engineered, and manufactured in the United States using advanced CNC machining technology and rigorous quality-control processes. We stand behind our products with a 100% lifetime warranty against manufacturing defects and our exclusive Spring for Life guarantee that ensures your spring is replaced free of charge if it ever wears out. When you choose Shield Arms, you're choosing American innovation, precision manufacturing, and a company committed to supporting the shooting community with products engineered to perform when it matters most.
