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Lewis Machine & Tool
Overview
The LMT Piston Full Auto Bolt Carrier Group Gen 2 is designed for the 5.56 NATO caliber, providing a reliable and robust option for builders looking to enhance the function of their AR-15 platform. This full auto-capable bolt carrier group features a piston system that improves reliability by reducing gas blowback and carbon fouling in the receiver, making it easier to maintain during extended shooting sessions. This component is commonly found in builds intended for competitive shooting or tactical applications, where reliability and performance are critical.
LMT Piston Full Auto Bolt Carrier Group Gen 2 - 5.56 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 April 2026. All time, it ranks #221 of the 445 bolt carrier groups builders have added.
It was out of stock everywhere we track for all of August 2026, and today the one retailer we track is out of stock. Listed prices start at $425.70 at Primary Arms for when it comes back.
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We ranked every bolt carrier group by how often it shows up in real builds on GunPartPicker.
Read the guide: The Most Trusted AR-15 BCGs →Check it against the live catalog:
The part most often added in each category by the 3 builds that include this one

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Forward Controls Design GBF .750 Low Profile Gas Block - GBF
Builds in the community that include the LMT Piston Full Auto Bolt Carrier Group Gen 2 - 5.56
| Build | Parts | Total |
|---|---|---|
![]() | 17 | $3983.07 |
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