CMMG MK4 .223 Remington AR Lower, Black - 55CA102AB
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CMMG
Overview
The CMMG MK4 .223 Remington AR Lower is a stripped lower receiver designed for the AR-15 platform, crafted from durable 7075-T6 aluminum and finished with a Cerakote in black. This lower is compatible with a multi-caliber setup, allowing builders to customize their firearms for various applications. It is a forged design, which adds strength and reliability, making it a solid choice for builds that typically feature a mid-length gas system and utilize the .223 Wylde caliber.
Specifications
August 2026 on GunPartPicker
CMMG MK4 .223 Remington AR Lower, Black - 55CA102AB ranked #41 of the 507 lower receivers builders added on GunPartPicker in August 2026, behind the Colt M4 Commando 5.56mm Semi-Auto Lower Receiver Assembly With "LE" Prefix, with about 1 in every 250 lower receivers added to builds. Up from #64 in July. Builds with this lower receiver are mostly chambered in 5.56 NATO (75%, then 300 Blackout 13%), split between mid-length (50%) and carbine-length (38%) gas systems, and nearly all AR-15.
It was hard to find in August 2026, in stock on only 7 of the 26 days we checked, and today 3 of the 7 retailers we track have it in stock. The best price crept up from $94.69 to $100.02 over August 2026. Buying today, the lowest price is $100.02 at Classic Firearms, above August's low of $94.69, 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 72 builds that include this one
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Build Configuration Breakdown
Aggregated and anonymized data showing how builders use 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.
Builds Featuring This Part
See all 4 →Builds in the community that include the CMMG MK4 .223 Remington AR Lower, Black - 55CA102AB
| Build | Parts | Total |
|---|---|---|
 | 20 | $802.16 |
 | 26 | $2829.88 |
 | 11 | $1178.61 |
 | 11 | $1432.46 |
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