Rosco Manufacturing - 26,750 Rounds of Full Auto - Barrel Autopsy

Published on April 23, 2020
Duration: 17:12

This detailed barrel autopsy on a Rosco Manufacturing 10.5" 5.56 NATO barrel reveals its performance after 26,750 rounds of full-auto fire. While throat and headspace remained surprisingly good, severe muzzle and gas port erosion were identified as the primary causes of accuracy degradation and keyholing. The inspection methodology highlights critical wear points to assess barrel longevity.

Quick Summary

Severe muzzle erosion was the primary cause of accuracy degradation and keyholing in the Rosco Manufacturing barrel after 26,750 full-auto rounds. Gas port erosion also contributed significantly to the performance decline.

Chapters

  1. 00:00Introduction: 26,750 Round Full Auto Test
  2. 00:50Inspection Methodology & Tools
  3. 02:05Initial Barrel Inspection & Markings
  4. 03:15Borescope Analysis: Fouling & Cracking
  5. 07:40Gas Port Measurement
  6. 09:30Muzzle Erosion & Accuracy Failure
  7. 10:05Throat Erosion & Headspace Check
  8. 12:00Barrel Straightness & Thread Concentricity
  9. 13:30Final Assessment: Barrel Longevity

Frequently Asked Questions

What caused the accuracy issues in the Rosco barrel after 26,750 full-auto rounds?

The primary cause of accuracy degradation and keyholing was severe muzzle erosion. Significant gas port erosion also contributed to the barrel's performance decline over its extensive lifespan.

How was the barrel's condition assessed after the high-round count test?

The inspection included gauging the gas port size, checking thread concentricity, headspace, muzzle and throat erosion using specialized tools, and internal visual inspection via borescope.

What was the condition of the throat and headspace on the Rosco barrel?

Surprisingly, the throat erosion was only at level 4 out of 11, indicating good durability. Headspace also remained well within safe limits, not even closing on a 'no-go' gauge.

What are the key takeaways regarding barrel longevity from this test?

This test demonstrates that while components like the throat and headspace can remain robust, muzzle and gas port erosion are critical failure points for accuracy and function after extreme use, even with quality barrels.

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