Fmk Ar15 Polymer Lower Receiver Fde
FMK Firearms
$37.69
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FMK Firearms
Fmk Ar15 Polymer Lower Receiver Fde
The FMK AR1 eXtreme Polymer Lower Receiver in Flat Dark Earth delivers a battle-ready foundation for your custom AR-15 build, combining American-made craftsmanship with an advanced composite polymer that outperforms traditional aluminum in both weight and resilience.
- Proprietary high-impact composite polymer engineered for extreme strength and durability
- Weighs just 4.3 oz — significantly lighter than standard aluminum lowers
- Accepts all standard MIL-SPEC uppers, including calibers up to .50 Beowulf
- Compatible with most current AR-15 lower parts kits, grips, and stocks
- Flexible polymer construction rebounds from impacts that would dent or crack aluminum
- Backed by a lifetime warranty and proudly manufactured in the USA
Who This Is For
The FMK AR1 eXtreme FDE lower receiver is ideal for AR-15 builders who want a lightweight, durable, and cost-effective foundation for their rifle. Whether you're assembling a range carbine, a home-defense build, or a truck gun that needs to handle rough conditions, this polymer lower delivers MIL-SPEC compatibility and long-term reliability without the weight penalty of a forged aluminum receiver.
Specifications
| Brand | FMK Firearms |
|---|---|
| Model | AR1 eXtreme |
| Color / Finish | Flat Dark Earth (FDE) |
| Material | Proprietary High-Impact Composite Polymer |
| Weight | 4.3 oz |
| Platform | AR-15 |
| Caliber Compatibility | Up to .50 Beowulf (MIL-SPEC uppers) |
| Parts Kit Compatibility | Standard AR-15 MIL-SPEC Lower Parts Kits |
| Country of Manufacture | United States of America |
| Warranty | Lifetime |
Frequently Asked Questions
Is this lower receiver compatible with my existing AR-15 upper and parts kit?
Yes. The FMK AR1 eXtreme is designed to accept all standard MIL-SPEC AR-15 uppers, including those chambered up to .50 Beowulf. It is also compatible with most standard AR-15 lower parts kits, grips, and stocks on the market, making it a versatile drop-in foundation for nearly any AR-15 build.
How does a polymer lower compare to a forged aluminum lower in terms of strength?
FMK's proprietary composite polymer is engineered to flex and rebound under impact rather than dent, crack, or shatter like forged aluminum can under extreme stress. While aluminum lowers are the traditional choice, the AR1 eXtreme's advanced polymer construction offers comparable functional strength with a significant weight advantage — making it particularly well-suited for field use and lightweight builds.
Does this lower receiver ship as a complete lower or stripped?
The FMK AR1 eXtreme is a stripped polymer lower receiver, meaning it does not include a lower parts kit, stock, buffer tube, or pistol grip. You will need to purchase these components separately to complete your build. This gives you full flexibility to choose the trigger group, grip, and furniture that best suit your intended use.
