Smyth Busters: Can an AR-15 Fire Full Auto With an M16 Carrier?

Published on July 29, 2020
Duration: 3:15

This guide, drawing from expert instruction by Caleb and Steve from Brownells, clarifies the common misconception that installing an M16 bolt carrier group (BCG) into an AR-15 will make it fire full-auto. It details the visual differences between AR-15 and M16 BCGs, emphasizing the M16's auto sear trip lug. Crucially, it explains that a full-auto conversion requires more than just the BCG, necessitating a compatible lower receiver and trigger group. The guide concludes with a vital reminder about NFA regulations and consulting local laws.

Quick Summary

Installing an M16 bolt carrier group (BCG) into an AR-15 does not make it fire full-auto. The AR-15 lower receiver lacks the auto sear and trigger components for automatic fire. An M16 BCG has an extended rear lug to trip the auto sear, a feature absent on AR-15 BCGs. Full-auto conversion requires additional parts and strict adherence to NFA regulations.

Chapters

  1. 00:00Introduction to the Myth
  2. 00:33BCG Comparison
  3. 01:08Required Components for Full-Auto
  4. 01:49Semi-Auto Conversion Kits
  5. 02:36Conclusion and Legal Disclaimer

Frequently Asked Questions

Can an AR-15 fire full-auto if I install an M16 bolt carrier group?

No, installing an M16 bolt carrier group (BCG) into a standard AR-15 will not make it fire full-auto. The AR-15 lower receiver lacks the necessary auto sear and trigger components required for automatic fire, even with an M16 BCG.

What is the main difference between an AR-15 and an M16 bolt carrier group?

The primary difference is the rear lug. An M16 BCG has an extended rear lug designed to trip the auto sear for full-auto fire, while an AR-15 BCG has this lug shaved off to prevent auto sear engagement and ensure semi-automatic function.

What else is needed to make an AR-15 fire full-auto besides an M16 bolt carrier group?

To achieve full-auto fire, you need more than just an M16 BCG. A compatible lower receiver with an auto sear, a full-auto trigger group, and adherence to all federal (NFA) and local regulations are essential. Without these, the firearm remains semi-automatic.

Are there legal implications to modifying a firearm for full-auto fire?

Yes, modifying a firearm to fire automatically is heavily regulated under the National Firearms Act (NFA). It requires federal registration, licensing, and payment of a tax stamp. Always consult and comply with all federal, state, and local laws.

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