CMMG AR-15 Carbine Buffer Tube Extension Kit
CMMG
$64.69
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CMMG
CMMG AR-15 Carbine Buffer Tube Extension Kit
The CMMG Receiver Extension Kit for AR-15 Carbine builds delivers everything you need to complete your lower receiver in a single, mil-spec package — ideal for new builds and lower completion projects alike.
- Complete kit includes receiver extension, end plate, buffer, and spring
- 6-position adjustable carbine receiver extension for versatile stock fitment
- Mil-spec diameter ensures compatibility with standard AR-15 carbine stocks
- High-quality anodized aluminum construction for durability and corrosion resistance
- Compatible with standard 5.56mm NATO and .223 Rem AR-15 rifle builds
- Reliable carbine buffer and spring tuned for consistent cycling performance
Who This Is For
This kit is perfect for AR-15 enthusiasts completing a stripped lower receiver, hobbyist builders assembling their first rifle, or experienced shooters replacing worn buffer components. If you want a trustworthy, mil-spec solution that takes the guesswork out of sourcing individual parts, CMMG's all-in-one receiver extension kit is the smart choice.
Specifications
| Brand | CMMG |
|---|---|
| Platform | AR-15 |
| Kit Contents | Receiver Extension, End Plate, Carbine Buffer, Buffer Spring |
| Extension Type | Carbine, 6-Position |
| Diameter Standard | Mil-Spec |
| Material | Anodized Aluminum |
| Caliber Compatibility | 5.56mm NATO / .223 Rem |
| Category | Buffers & Buffer Tubes |
Frequently Asked Questions
What is the difference between mil-spec and commercial receiver extensions?
A mil-spec receiver extension has a slightly smaller outer diameter (approximately 1.148") compared to a commercial-spec tube (approximately 1.168"). This distinction matters when selecting a buttstock — mil-spec stocks require a mil-spec tube and vice versa. The CMMG kit uses a mil-spec diameter, which is the more widely compatible and preferred standard among AR-15 builders and manufacturers.
Will this kit work with my existing AR-15 lower receiver?
Yes. This CMMG receiver extension kit is designed to fit any standard AR-15 lower receiver with a mil-spec buffer tube threaded interface. It is compatible with direct impingement AR-15 builds chambered in 5.56mm NATO or .223 Rem. It is not intended for pistol builds using a pistol-length buffer tube or for AR-10/LR-308 platforms.
Do I need any additional parts to complete my lower receiver with this kit?
This kit covers the buffer tube assembly components — receiver extension, end plate, carbine buffer, and buffer spring. To fully complete your AR-15 lower, you will also need a lower parts kit (LPK) that includes the trigger group, pistol grip, and magazine release components, as well as a compatible carbine buttstock. CMMG's kit gives you a solid foundation to build from.
