CMMG AR-15 Fastback Receiver Extension Mil-Spec
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CMMG
Overview
The CMMG AR-15 Fastback Receiver Extension is a Mil-Spec buffer tube designed for reliable performance in your build. As a tube-only assembly, it provides the essential structure for housing your buffer and spring, ensuring proper cycling in your AR-15 platform. This component is often found in builds chambered for .308 Win, making it a practical choice for those looking to enhance their precision rifle setup.
Specifications
August 2026 on GunPartPicker
CMMG AR-15 Fastback Receiver Extension Mil-Spec ranked #39 of the 48 buffer tubes builders added on GunPartPicker in August 2026. Builders have been adding it to their builds on GunPartPicker since February 2026. All time, it ranks #40 of the 63 buffer tubes builders have added.
It was in stock most days in August 2026, and today 2 of the 3 retailers we track have it in stock. The best price drifted down from $59.95 to $56.15 over August 2026 without a real sale. Buying today, the lowest price is $59.95 at CMMG, above August's low of $56.15, so a better deal may come back.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 35 retailers
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Frequently Built With
The part most often added in each category by the 7 builds that include this one
Fortis Lightweight Enhanced AR-15 End Plate, Gold - LE-Black-K1-GOLD
Magpul Miad Gen 1.1 Grip KIT Polymer Gray
Strike Industries Ambidextrous Magazine Release, Black - ARAMBIMRBK
ODIN Works AR-15 Extended Bolt Catch
JP Enterprises Gen 2 AR 15 Silent Captured Spring Builder W Alternative Spring Pack H2 Buffer Version
Radian A-DAC 15 Lower Receiver
Build Configuration Breakdown
Aggregated and anonymized data showing how builders use this product
PlatformBased on real build data showing which platform (AR-15, AR-10, AR-9) builders pair with this product.
CaliberBased on real build data showing which calibers builders choose alongside this product.
Gas SystemBased on real build data showing which gas system lengths builders use with this product.
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