What’s the difference between an AR15 and an M16?

Published on September 23, 2025
Duration: 6:25

This video clarifies the distinction between AR-15 and M16 designations, explaining that M16/M4 are US government designations for AR-15 platform rifles. It details how Colt initially used 'AR-15' for its commercial line while the government adopted 'M16' for selective-fire variants. The video also touches on the M4 designation and its trademark history, emphasizing that the core internal operating system defines an AR-15, regardless of external markings or selective-fire capability.

Quick Summary

The M16 and M4 are US government designations for rifles based on the AR-15 platform. Historically, 'AR-15' was Colt's commercial designation for semi-automatic variants, while 'M16' denoted selective-fire military versions. The core internal piston design defines an AR-15, regardless of manufacturer or fire mode.

Chapters

  1. 00:08Introduction: AR-15 vs M16 Question
  2. 00:29The Core Difference: Nothing
  3. 00:31M16/M4 as US Government Designations
  4. 00:45Early Colt AR-15 Markings
  5. 00:53Government Adoption: XM16E1 and M16
  6. 01:13Dropping the AR-15 Designation
  7. 01:24Stoner's Design: The AR-15 Foundation
  8. 01:43Origin of AR-15 as Semi-Automatic Only
  9. 01:50Colt's Selective Fire Line: M16 Designations
  10. 02:02Colt's Internal M16 Designations
  11. 02:20M16A2 Variations
  12. 02:31Barrel Lengths and Designations
  13. 03:01Colt's AR-15 Trademark
  14. 03:10Other Manufacturers' Designations
  15. 03:20AR-15 Confined to Colt Use
  16. 03:27Analogy: M9 Pistol
  17. 03:40The M4 Carbine
  18. 03:48M4 Technical Data
  19. 03:58Colt's Commercial M4 Use
  20. 04:13M4 Trademark Issues
  21. 04:37M4 Designation Now Open
  22. 04:46Visual Examples: Colt AR-15 US Military Guns
  23. 05:05Colt's Historical Nomenclatures
  24. 05:21All These Guns Are AR-15s
  25. 05:24AR10 Variations Explained
  26. 05:34SR25 and LMT MRP as AR10
  27. 05:57Differentiating External Piston Systems
  28. 06:05External Piston is Not AR-15
  29. 06:20Conclusion and Call to Action

Frequently Asked Questions

What is the fundamental difference between an AR-15 and an M16?

Fundamentally, there is no difference in the core design. The M16 and M4 are US government designations for rifles based on the AR-15 platform. Historically, 'AR-15' was used by Colt for commercial semi-automatic variants, while 'M16' denoted selective-fire military versions.

Why did Colt trademark the term AR-15?

Colt held a trademark on the term 'AR-15' which allowed them to be the sole company to use it for their rifles. This restriction forced other manufacturers to create new designations for their AR-15 platform firearms.

Are M16 and M4 rifles always selective-fire?

While M16 and M4 are US government designations often associated with selective-fire capability (full-auto or burst), the AR-15 platform itself can be manufactured in semi-automatic-only configurations by various companies.

Can any company now use the term M4 on their rifles?

Yes, after a trademark dispute, the M4 designation's trademark was nullified because it was a US government designation and in common use. This means any company is now free to use the term 'M4' on their rifles.

What distinguishes an AR-15 from other similar-looking rifles?

An AR-15 is defined by its adherence to Eugene Stoner's internal piston operating system. Rifles with external piston systems, even if they look similar, are considered different operating systems and are not classified as AR-15s.

Related News

All News →

More General Videos You Might Like

More from SmallArmsSolutions

View all →