The AR-15 platform's popularity stems from its modularity and adaptability. However, this versatility necessitates meticulous attention to detail, especially when it comes to ensuring the proper function and safety of your firearm. One critical tool for maintaining the integrity of your AR-15 is the go/no-go gauge. This simple device plays a vital role in verifying the headspace of your rifle's chamber, a crucial measurement affecting both accuracy and safety. Understanding its use is paramount for responsible AR-15 ownership.
What is a Go/No-Go Gauge?
A go/no-go gauge for an AR-15 is a precision-machined tool consisting of two separate gauges:
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Go Gauge: This gauge is sized to the exact specifications of a correctly chambered round. It should slide smoothly into the chamber without resistance. If the go gauge fits correctly, it indicates the chamber's headspace is within the acceptable range.
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No-Go Gauge: This gauge is slightly larger than the go gauge, representing the maximum acceptable headspace. If the no-go gauge fits into the chamber, it indicates that the headspace is nearing the limit and needs attention. If it doesn't fit, it confirms the headspace is within safe limits.
These gauges allow gun owners to quickly and easily check headspace without the need for specialized tools or expertise.
Why is Checking Headspace Crucial?
Headspace refers to the distance between the breech face of the barrel and the head of a cartridge when the cartridge is fully seated in the chamber. Incorrect headspace can lead to several serious issues:
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Failure to Fire: Excessive headspace can prevent the firing pin from striking the primer with sufficient force.
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Squib Loads: A squib load (a round that doesn't fully detonate) can become lodged in the barrel, potentially causing catastrophic damage upon subsequent firing.
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Case Rupture: Insufficient headspace can cause excessive pressure buildup, resulting in a ruptured cartridge case, potentially causing injury to the shooter.
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Accuracy Issues: Incorrect headspace directly impacts the precision of your shots. Consistent and accurate headspace is essential for optimal bullet placement.
How to Use a Go/No-Go Gauge
Using a go/no-go gauge is straightforward, but it demands careful attention to detail:
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Safety First: Always ensure the firearm is unloaded and clear of ammunition. Visually inspect the chamber and ensure it's empty.
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Insert the Go Gauge: Carefully insert the go gauge into the chamber. It should slide in smoothly and easily. If it doesn't, there might be an obstruction or the chamber is damaged.
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Insert the No-Go Gauge: If the go gauge fits correctly, insert the no-go gauge. The no-go gauge should not fit easily into the chamber. Some slight resistance might be felt, but it shouldn't go in without significant force.
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Interpret the Results: If both gauges behave as described above, your headspace is within acceptable limits. If the no-go gauge fits easily, your headspace is excessive, and you should seek professional help from a qualified gunsmith.
Choosing the Right Go/No-Go Gauge
It's essential to purchase a go/no-go gauge specifically designed for your AR-15 chamber. Different calibers (.223 Wylde, 5.56 NATO, etc.) have different specifications, and using the wrong gauge can lead to inaccurate readings and potentially unsafe situations. Always confirm the gauge's compatibility with your specific AR-15 chamber before use.
Conclusion
Regularly checking your AR-15's headspace using a go/no-go gauge is an essential part of responsible gun ownership. This simple yet crucial step significantly contributes to the safety and accuracy of your firearm. By investing in a quality gauge and understanding its proper use, you can help prevent potentially hazardous situations and maintain the performance of your AR-15. Always prioritize safety and seek professional assistance if you have any doubts or encounter unexpected results.
