BROWNELLS BRN 5.56MM MAXIMUM HEADSPACE GAUGE

The Brownells BRN 5.56mm Maximum Headspace Gauge is a precision inspection tool designed to verify maximum allowable headspace in 5.56 NATO M16 and AR-15 rifles. Manufactured to the special dimensions used by the Colt factory, this gauge provides an essential safety and serviceability check for rifles that have experienced heavy use, undergone rebarreling, or received bolt and barrel component replacements.

Unlike standard GO and NO-GO gauges, this gauge measures the maximum factory-acceptable headspace limit, helping armorers and gunsmiths determine whether a rifle remains within serviceable specifications. Excessive headspace can contribute to reliability issues, accelerated component wear, and potential cartridge case problems, making routine inspection an important part of firearm maintenance.

Constructed from hardened, ground steel for long-term accuracy and durability, this gauge is a valuable addition to any AR-15 armorer's toolkit.

FEATURES

• Designed specifically for 5.56 NATO M16 and AR-15 platforms
• Manufactured to Colt factory maximum headspace dimensions
• Checks maximum allowable service headspace
• Ideal for inspecting heavily used rifles
• Useful after barrel, bolt, or upper receiver replacement
• Precision-ground for accurate measurements
• Hardened steel construction for durability and wear resistance
• Essential tool for armorers, gunsmiths, and serious AR owners

SPECIFICATIONS

• Manufacturer: Brownells
• Gauge Type: Maximum Headspace Gauge
• Caliber: 5.56 NATO
• Maximum Headspace Measurement: 1.4736"
• Material: Hardened Ground Steel
• Overall Length: 1.65" (4.2 cm)
• Length is not the headspace dimension
• Diameter: 0.3655" (9.3 mm)

CUSTOMER INSIGHTS

AR-15 builders and armorers frequently use maximum headspace gauges when evaluating rifles with high round counts or when mixing bolts and barrels from different manufacturers. Customers appreciate having a dedicated maximum-specification gauge because it allows them to quickly determine whether a firearm remains within acceptable service limits. Many consider it a critical diagnostic tool for inspecting duty rifles, training carbines, and surplus firearms.

The Brownells BRN 5.56mm Maximum Headspace Gauge is a precision-built inspection tool that verifies whether a 5.56 NATO AR-15 or M16 remains within Colt's maximum acceptable headspace specification of 1.4736 inches. Made from hardened ground steel and intended for serviceability checks on heavily used or reconfigured rifles, it is an essential tool for maintaining the safety, reliability, and longevity of the AR platform.

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