What's the Difference? NO-GO VS Field Gauge 7.62x39

Published on March 6, 2019
Duration: 6:16

This guide explains the critical differences between No-Go and Field headspace gauges for 7.62x39 firearms, particularly AK-style rifles. It details how to use these gauges to check for safe headspace, emphasizing that No-Go gauges are for new firearms and Field gauges are for used firearms. The video demonstrates precise measurements of gauge dimensions, including shoulder height and base diameter, highlighting the subtle but important variations that affect firearm safety and function, and notes the relevance of CIP specifications.

Quick Summary

For 7.62x39 firearms, a No-Go gauge is used to ensure new firearms meet safe headspace specifications, while a Field gauge determines if a fired firearm has exceeded maximum allowable headspace. AK-style rifles, known for their robust design, may require Field gauge checks due to their tendency to 'move metal' after firing.

Chapters

  1. 00:00Introduction to Headspace Gauges
  2. 00:15Visualizing No-Go vs. Field Gauges
  3. 00:45Measuring No-Go Gauge Dimensions
  4. 01:20Measuring Field Gauge Dimensions
  5. 01:45Shoulder Height Comparison
  6. 02:25Throat/Taper Measurement
  7. 02:58Base Diameter Measurement
  8. 03:15Summary of Gauge Differences
  9. 03:45CIP vs. SAAMI Standards
  10. 04:00Application of No-Go vs. Field
  11. 04:30AK Design and Headspace
  12. 05:25Conclusion and Recommendation

Frequently Asked Questions

What is the primary difference between a No-Go and a Field headspace gauge for 7.62x39 firearms?

A No-Go gauge checks if a new firearm's headspace is within safe manufacturing limits. A Field gauge checks if a fired firearm has exceeded the maximum allowable headspace, indicating it may be unsafe to fire.

Why are headspace gauges important for AK-style firearms like the 7.62x39?

AKs are built with looser tolerances and can 'move metal' after firing. Headspace gauges, especially Field gauges, are crucial for ensuring these firearms remain safe to operate after use.

Can I use a No-Go gauge to check a used 7.62x39 AK?

No, a No-Go gauge is only for new firearms. Once a firearm has been fired, only a Field gauge should be used to check for excessive headspace.

What are the typical measured differences between 7.62x39 No-Go and Field gauges?

The differences are subtle. The Field gauge typically has a slightly higher shoulder height (e.g., 31.44mm vs. 30.66mm for No-Go) and a slightly larger base diameter, allowing for more headspace.

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