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CMMG
Overview
The CMMG 5.56 Complete Bolt Carrier Group is designed for the 5.56 NATO caliber, ensuring reliable cycling and performance in your AR-15 build. With a nitride finish, this BCG enhances durability and corrosion resistance, contributing to smoother operation and easier maintenance. This component is often found in mid-length gas system builds, making it a solid choice for those looking to optimize their rifle's performance.
CMMG 5.56 Complete Bolt Carrier Group, Black - 55BA419
CMMG 5.56 Complete Bolt Carrier Group, Black - 55BA419 ranked #77 of the 229 bolt carrier groups builders added on GunPartPicker in August 2026. Builders have been adding it to their builds on GunPartPicker since February 2026. All time, it ranks #63 of the 445 bolt carrier groups builders have added. Builds with this bolt carrier group are nearly all chambered in 5.56 NATO, nearly all on rifle-length gas, and mostly AR-15 (75%, then AR-10 25%).
Availability is good: it was in stock at one retailer or another nearly every day in August 2026, and today 6 of the 7 retailers we track have it in stock. It dipped to $128.89 at GritR Sports for a stretch in August 2026, under its usual $134.99 to $161.49, so sales do come around. Buying today, the lowest price is $139.49 at Optics Planet, above August's low of $128.89, so a better deal may come back.
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Aggregated and anonymized data showing how builders use this product
Builds in the community that include the CMMG 5.56 Complete Bolt Carrier Group, Black - 55BA419
| Build | Parts | Total |
|---|---|---|
 | 15 | $3568.09 |
 | 17 | $1484.73 |
 | 14 | $847.15 |
 | 13 | $2951.06 |
 | 21 | $989.34 |
 | 25 | $1053.65 |
1 global rating
Top reviews
CMMG 5.56 BCG runs reliably on a carbine 16in build. The black finish is more glossy than the matte I expected from product photos, only visible side by side. Gas key staked properly.
