Good & Bad Gas/Carrier Keys - Mil-spec is not Mil-spec

Published on April 14, 2020
Duration: 2:00

This video demonstrates the critical importance of inspecting gas keys for proper fit using a go/no-go gauge. The instructor highlights that 'mil-spec' components can vary significantly in quality, with some being undersized or oversized. A proper fit ensures reliable function, preventing issues like the bolt carrier getting stuck.

Quick Summary

Inspect gas keys using a go/no-go gauge to ensure proper fit. The 'green' side should slide in smoothly, while the 'red' side should not enter. This prevents malfunctions caused by undersized or oversized keys, ensuring reliable firearm operation.

Chapters

  1. 00:00Introduction to Gas Key Inspection
  2. 00:17Using the Go/No-Go Gauge
  3. 00:36Testing a Good Component
  4. 00:47Identifying an Oversized Bore
  5. 01:13Example of a Total Failure (Oversized Key)
  6. 01:38Why Inspection is Necessary

Frequently Asked Questions

Why is it important to inspect a gas key before installing it on a bolt carrier?

Inspecting a gas key ensures it has the correct fit. An undersized key can lead to reliability issues, while an oversized key can cause the bolt carrier to seize, preventing removal from the firearm. This inspection prevents potential malfunctions and ensures proper operation.

What tool is used to check the fit of a gas key?

A specialized go/no-go gauge designed for carrier keys is used. This tool has two sides, typically green for 'go' and red for 'no-go,' which are inserted into the gas key bore to verify its dimensions.

What does it mean if the 'green' side of a carrier key gauge goes in smoothly?

If the 'green' side of the carrier key go/no-go gauge slides smoothly into the bore, it indicates that the bore is within the acceptable tolerance range and is not undersized. This is a good sign for proper fit.

What is the consequence of an oversized gas key on a bolt carrier?

An oversized gas key can cause the bolt carrier to lock itself into the receiver. This means that when the bolt is closed, the carrier key will bind, making it impossible to pull the bolt carrier out of battery, rendering the firearm inoperable.

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