Brownells Ar-15/M16 Colt 5.56X45 Nato Headspace Gauge 1.4736''

If you're building, rebuilding, or maintaining an AR-15 or M16 platform rifle, headspace is one of those critical dimensions that separates a safe, reliable gun from a ticking problem. The Brownells AR-15/M16 Colt 5.56×45 NATO Headspace Gauge is a gunsmithing tool that lets you verify your rifle's headspace against Colt's factory specifications—the standard that defines the maximum safe tolerance for this platform. Whether you're checking a barrel swap you just completed, evaluating a used rifle, or troubleshooting a gun that's seen hard use, this precision gauge gives you the confidence that your headspace is within spec.

Headspace is the distance from the bolt face to the chamber's reference datum. Too much headspace and you risk dangerous cartridge movement, extraction failures, and potential safety issues. Too little and feeding becomes unreliable. The Brownells gauge is manufactured to Colt's exact factory dimensions, which means it's engineered to the dimensions that define acceptable AR-15/M16 headspace limits. This is the tool professional gunsmiths and serious shooters reach for when precision matters.

Whether you're a competitive shooter, a builder who demands accuracy, or someone who wants to verify the condition of a rifle before you send rounds downrange, this headspace gauge removes the guesswork. It's a small tool with outsized importance—the kind of thing that takes five minutes to use but can prevent a world of trouble.

Key Features

• Manufactured to Colt factory specifications for AR-15/M16 rifles
• Measures maximum factory acceptable headspace
• Essential for verifying headspace after barrel replacement
• Suitable for rifles in active use or after extensive service
• Precision gunsmithing tool for 5.56×45 NATO caliber

Specifications

Frequently Asked Questions

Why do I need an AR-15 headspace gauge?

Headspace directly affects safety and reliability. After a barrel replacement, or if you're evaluating a used rifle, a headspace gauge tells you whether the chamber-to-bolt-face distance is within Colt's factory limits. Excess headspace can lead to extraction problems and safety issues; checking it is standard procedure for gunsmiths and serious builders.

Will this gauge work on my AR-15 or M16?

This Brownells headspace gauge is manufactured to Colt factory specifications for AR-15 and M16 rifles chambered in 5.56×45 NATO. It measures against the maximum factory acceptable headspace for these platforms.

Can I use this after replacing my barrel?

Yes. Verifying headspace after a barrel swap is one of the most common uses for this gauge. It ensures your new barrel is properly seated and headspaced within factory limits.

What is the 1.4736" dimension?

The 1.4736" specification represents the maximum factory acceptable headspace measurement for AR-15/M16 rifles to Colt's dimensions. This is the standard reference for this platform.