What is the LIMIT for 6mm ARC? (DON'T TRY THIS)

Published on February 9, 2026
Duration: 20:34

This video details extreme pressure testing of the 6mm ARC cartridge using both a bolt-action rifle and an AR-15 platform. The experiment pushes the limits of Alpha Munitions brass with 8208 XBR powder, achieving velocities exceeding factory specifications and even 6 Creedmoor. The testing culminates in destructive attempts using a fast-burning pistol powder in an AR-15, demonstrating the significant forces involved and the potential for catastrophic failure. The presenter, Gavin Gear, emphasizes that these tests are for research only and should not be replicated due to extreme danger.

Quick Summary

Extreme pressure testing of 6mm ARC with 8208 XBR powder in a bolt-action rifle reached 3092 ft/s, exceeding factory 6mm ARC and 6mm Creedmoor velocities. Using a fast-burning pistol powder in an AR-15 led to catastrophic failure, destroying the bolt carrier group and magazine.

Chapters

  1. 00:05Introduction: 6mm ARC Limits & Brass Destruction
  2. 00:24Gavin Gear's Extreme Testing Approach
  3. 00:38Safety Warning: Do Not Attempt This
  4. 00:54Recap: Previous High-Pressure Tests (.308, 6GT)
  5. 02:26The Question: What About 6mm ARC?
  6. 02:41Choosing Powder: 8208 XBR for 6mm ARC
  7. 03:00Bolt Gun Setup for Testing
  8. 03:50First Hits with 6mm ARC Bolt Gun
  9. 04:04Alpha Munitions Brass & OCD Technology
  10. 04:23Loading Strategy: Incremental Grain Increases
  11. 05:04Chronograph Data Collection
  12. 05:19Velocity Data: 24 Grains to 29 Grains
  13. 06:28Subtle Pressure Signs Observed
  14. 06:37Pushing to 30 Grains: Breaking 3000 FPS
  15. 06:53Maximum Load Test: 31 Grains
  16. 07:14Results of 31 Grain Load: Velocity & Pressure
  17. 07:44Comparison to Hornady Factory Specs
  18. 08:39Conclusion: Over Pressure, Brass Held Up
  19. 08:53Exceeding 6 GT and 6 Creedmoor Performance
  20. 09:08Next Experiment: AR-15 Platform
  21. 09:31AR-15 Testing: Increased Risk
  22. 09:45AR-15 Velocity Data: 23 Grains to 29 Grains
  23. 10:17Intense Pressure Signs in AR-15
  24. 10:47AR-15 Testing with Remote Trigger
  25. 10:56AR-15: 30 Grains and 31 Grains Results
  26. 11:22Reasons for Lower Velocity in AR-15
  27. 11:38AR-15 Held Together (with Appropriate Powder)
  28. 11:43Destructive Test: Inappropriate Powder
  29. 12:07Using Hodgdon Universal Clays
  30. 12:24Filling Case to Top with Pistol Powder
  31. 13:01Firing the Destructive Load
  32. 13:35The Explosion: AR-15 Destruction
  33. 14:14Examining the Damaged AR-15 Components
  34. 15:15AR Destruction Analysis: Venting Gases
  35. 15:48Test Results Summary: Alpha Brass Strength
  36. 16:07Precision Example: 6 Dasher Build
  37. 16:25Bolt Action Pressure Sign Analysis: Base Diameter
  38. 17:41Graphs: Velocity, Base Diameter, Extractor Groove Growth
  39. 17:59Extreme Velocity Achieved in AR Destruction
  40. 18:41Final Thoughts: Pushing Limits
  41. 19:04AR-15 Destruction Recap
  42. 19:34Viewer Engagement: Comments & Future Content
  43. 19:42Conclusion & Subscription Reminder

Frequently Asked Questions

What is the maximum safe load for 6mm ARC with 8208 XBR powder?

In this extreme pressure test, 31 grains of 8208 XBR in Alpha Munitions brass for 6mm ARC showed significant pressure signs like ejector swipe and base diameter growth. While the brass held up, this is considered over-pressure and not a recommended load for regular use. Always consult reliable load data for safe maximums.

How does the 6mm ARC perform at extreme pressures compared to factory loads?

This test pushed 6mm ARC handloads to 3092 ft/s, significantly exceeding Hornady's factory 6mm ARC spec of 2750 ft/s and even their 6mm Creedmoor spec of 2960 ft/s. This demonstrates the cartridge's potential when pushed beyond standard limits.

What happened when an AR-15 was subjected to extreme pressure with a fast-burning pistol powder?

Using a fast-burning pistol powder like Hodgdon Universal Clays in a 6mm ARC AR-15 resulted in catastrophic failure. The bolt carrier group was destroyed, the magazine blew apart, and gases vented violently from the ejection port and bottom, indicating extreme over-pressure.

How can brass growth indicate high pressure in firearms?

Excessive pressure causes brass cases to expand. Measuring base diameter and extractor groove diameter after firing can reveal this. In this test, base diameter growth of 4.85 thousandths and extractor groove growth of 5.5 thousandths indicated significant pressure beyond SAAMI specifications.

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