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5.56mm Maximum Headspace Gauge - Brn Ar-15/M16 Colt 5.56x45 Nato Headspace Gauge 1.4736''''
Our editorial team reviews specifications, product data, and field-use information to keep pages accurate.
$46.45
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SKU: 319418033
Overview
This gauge is intended for checking maximum factory-acceptable headspace in M16 and AR-15 rifles built to Colt factory dimensions. It is a practical inspection tool for rifles that have seen extensive service or have been rebarreled, where confirming chamber condition is part of responsible maintenance. The gauge is made from hardened and ground steel and is sized for use as a precision reference rather than a general-purpose accessory. For hunters and shooters who maintain AR-pattern rifles, it supports careful evaluation without adding unnecessary complexity.
Why Hunters Choose the Brownells
Measures Maximum
Factory acceptable headspace for M16/AR-15
Made Colt
Factory special dimensions for specified
Useful Checking
Extensively serviced or rebarreled guns
Hardened Ground
Steel construction
Compact 1.65-inch
Overall length for easy handling
Key Features
- Measures maximum factory-acceptable headspace for M16/AR-15 rifles.
- Made to Colt factory special dimensions for 5.56x45 NATO applications.
- Useful for checking rifles that have seen extensive service or rebarreling.
- Hardened and ground steel construction.
- Overall length is 1.65 inches; diameter is .3655 inches.
Best Used For
- AR-15 or M16 owners checking maximum factory-acceptable headspace during routine maintenance
- Users inspecting rifles that have seen extensive service and need a precise chamber check
- Gunsmiths verifying headspace after rebarreling an M16 or AR-15 platform rifle
- Colt-pattern rifle owners wanting a factory-specified gauge for 5.56x45 NATO chambers
Specifications
| Compatibility | M16/AR-15 rifles |
|---|---|
| Diameter | .3655 in (9.3 mm) |
| Headspace Measurement | Maximum factory acceptable headspace |
| Material | Hardened and ground steel |
| Overall Length | 1.65 in (4.2 cm) |
Pros
- Measures maximum factory acceptable headspace for M16/AR-15 rifles
- Made to Colt factory special dimensions for specified rifles
- Useful for checking extensively serviced or rebarreled guns
- Hardened and ground steel construction
- Compact 1.65-inch overall length for easy handling
Considerations & Trade-offs
- Measures maximum factory acceptable headspace only, so it is a specific diagnostic tool rather than a general-purpose gauge set.
- Intended for M16/AR-15 rifles to Colt factory special dimensions, so it is best matched to that platform and specification.
- Most useful on rifles that have seen extensive service or have been rebarreled, which means it may be less relevant for routine checks on newer guns.
- The listed 1.65" overall size is not the headspace dimension, so the gauge’s physical length should not be confused with the measurement it verifies.
Suggested Comparisons
- AR-15/M16 headspace gauges
- Rifle maintenance and inspection tools
- Gunsmithing gauges and measuring tools
- 5.56 NATO chamber check tools
Suggested Accessories
- Headspace gauge set
- Cleaning kit
- Gun vise
- Bore cleaning rod
Frequently Asked Questions
What is this gauge used for on an AR-15 or M16 chambered in 5.56x45 NATO?
It is used to measure maximum factory acceptable headspace on M16/AR-15 rifles.
Is this gauge made to a factory specification?
Yes. The description says it is made to Colt factory special dimensions for M16/AR-15 rifles.
When would a hunter or armorer use a maximum headspace gauge?
The description says it is an essential check on guns that have seen extensive service or have been rebarreled.
What material is the gauge made from?
The listed specification says hardened and ground steel.
Does the listed 1.65 inch measurement refer to headspace?
No. The description specifically says 1.65 inches is the overall length of the gauge and is not the headspace dimension.