Warne Mag Ext S&w M&p 9/40 +5/4 Blk
Warne
$39.99
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Warne
Warne Mag Ext S&w M&p 9/40 +5/4 Blk
The Warne Mag Ext for S&W M&P 9/40 gives you a reliable, USA-made magazine extension that adds up to 5 rounds (9mm) or 4 rounds (.40 S&W) of extra capacity to your Smith & Wesson M&P pistol — without sacrificing the fit, finish, or function you depend on.
- Adds +5 rounds (9mm) or +4 rounds (.40 S&W) to your M&P magazine
- Machined from aircraft-grade 6061-T6 aluminum billet for maximum durability
- Type 2 hardcoat anodize finish resists abrasion, corrosion, and daily wear
- Ergonomic profile improves magazine insertion speed and reliability
- Finger grooves allow positive grip for stripping the mag when needed
- Secured with a Torx head screw and washer for a rock-solid, rattle-free fit
Who This Is For
This extension is ideal for competitive shooters, home defenders, and M&P enthusiasts who want more rounds on tap without switching to a higher-capacity magazine. It's also a smart upgrade for range training, where reduced reloads keep your practice sessions moving. The rugged aluminum construction and secure Torx fastener make it equally suited to duty use, IDPA/USPSA competition, or everyday carry setups where a full-size M&P is your platform of choice.
Specifications
| Brand | Warne |
|---|---|
| Compatible Firearm | Smith & Wesson M&P 9mm / .40 S&W |
| Capacity Increase | +5 rounds (9mm) / +4 rounds (.40 S&W) |
| Material | 6061-T6 Aluminum Billet |
| Finish | Type 2 Hardcoat Anodize – Matte Black |
| Retention Hardware | Torx Head Screw & Washer |
| Country of Origin | USA |
| Color | Black |
Frequently Asked Questions
Which S&W M&P models is this extension compatible with?
This Warne magazine extension is designed specifically for the full-size Smith & Wesson M&P chambered in 9mm or .40 S&W. It is not intended for the M&P Shield, M&P Compact, or M&P 2.0 Compact variants. If you're unsure about compatibility with your specific generation or model, we recommend verifying with the manufacturer or contacting our team at Goodland Guns before purchasing.
Is this extension legal to use in California?
California law restricts detachable firearm magazines to a maximum of 10 rounds. Because this extension increases capacity beyond 10 rounds when combined with a standard M&P magazine, it may not be legal for use with magazines that would exceed the 10-round limit in California. Warne does offer zero-capacity extension models designed to keep total capacity at or within the 10-round limit — please speak with our staff to find the compliant option for your needs.
Does the Warne Mag Ext affect the reliability or feeding of my M&P?
When properly installed using the included Torx head screw and washer, the Warne Mag Ext is engineered to maintain reliable feeding and function. The extension interfaces securely with your existing M&P magazine body, and the ergonomic design preserves proper spring tension and follower alignment. As with any magazine accessory, it's recommended to test function with your specific ammunition at the range before relying on it for duty or defensive use.
