Prototype 1 in 6'' Twist Green Mountain AR-15 4150 CMV CL Barrel Test (HD)

Published on December 17, 2014
Duration: 11:31

This video tests a prototype 14.5-inch Green Mountain AR-15 barrel with a 1:6 twist rate. The instructor evaluates its performance with various ammunition types, including 55-grain Wolf, 55-grain Freedom Munitions, 62-grain M855, and 75-grain Hornady TAP, at 100 yards. The testing aims to assess the benefits and potential drawbacks of a fast twist rate in a shorter barrel, specifically looking for jacket separation and group consistency.

Quick Summary

A prototype Green Mountain AR-15 barrel with a 14.5-inch length and a 1:6 twist rate was tested for performance. Despite initial questions about fast twist rates in shorter barrels, the testing showed no adverse effects, with the 55-grain Wolf ammo achieving a tight 1.25-inch group at 100 yards.

Chapters

  1. 00:31Introduction to R&D and Barrel Specs
  2. 00:44Barrel Details: 14.5", 1:6 Twist, 4150 Milspec
  3. 01:15Questions for Fast Twist Barrels
  4. 01:39Ammunition Selection for Testing
  5. 02:00Setting Up for 100 Yard Test
  6. 03:12First Group Analysis: 55gr Freedom Munitions
  7. 03:44Second Group: 62gr M855
  8. 04:44Third Group: 55gr Wolf
  9. 06:02Fourth Group: 75gr Hornady TAP
  10. 07:14Measuring Group Sizes
  11. 07:24Freedom Munitions 55gr Group: 2.5 inches
  12. 07:43M855 62gr Group: 1.75 inches
  13. 08:01Wolf 55gr Group: 1.25 inches (Surprising)
  14. 08:44Hornady TAP 75gr Group: 1.5 inches
  15. 09:01Initial Results and Conclusion
  16. 09:18Thanks to Green Mountain for the Barrel
  17. 09:30Availability and Future Offerings

Frequently Asked Questions

What are the specifications of the prototype Green Mountain AR-15 barrel tested?

The prototype barrel is 14.5 inches long, made from 4150 CMV steel to milspec standards, and features a unique 1:6 twist rate. This fast twist rate is designed to stabilize heavier bullets or potentially offer advantages in shorter barrels.

How did the 1:6 twist rate affect accuracy with different ammunition types?

The 1:6 twist barrel performed surprisingly well. The 55-grain Wolf ammunition yielded the tightest group at 1.25 inches, while the 75-grain Hornady TAP achieved 1.5 inches. The 62-grain M855 and 55-grain Freedom Munitions also produced respectable groups of 1.75 and 2.5 inches, respectively.

Were there any issues with lighter bullets like jacket separation with the fast twist rate?

During the test, no jacket separation issues were observed with the lighter weight bullets, including the 55-grain options. The instructor visually confirmed this during the shooting session and upon target inspection.

Is the Green Mountain 1:6 twist AR-15 barrel available for purchase?

As of the video's release, this specific prototype barrel is not yet available for purchase. Green Mountain is using this testing data for their R&D to decide on future product offerings.

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