Forster 5.56 Armorers Headspace Gauge Kit

The Forster 5.56 Armorers Headspace Gauge Kit is a practical tool for any gunsmith, armorer, or serious reloader who needs to verify chamber spec on AR-platform rifles. Headspace measurement is fundamental to safe, accurate rifle function—too tight and your bolt may not close; too loose and you risk unsafe pressure or reliability issues. This kit gives you the three-gauge system that lets you check 5.56 NATO chambers quickly without breaking down the bolt.

What makes this 5.56 headspace gauge kit different from standard gauges is its design: Forster manufactured these with a reduced rim and an ejector cutout, so you can insert and seat the gauges without disassembling the bolt. That's a huge time-saver in the field or at the bench. The kit includes three precision gauges covering the range you need: a 1.4646" Go gauge (minimum spec), a 1.4868" Max Field gauge (maximum safe spec), and a 1.4736" Midrange gauge (middle reference point). Running each gauge in succession tells you exactly where your chamber sits and whether it's in spec.

Whether you're building custom uppers, troubleshooting bolt-carrier compatibility, or just verifying a used rifle is safe to shoot, this tool pays for itself the first time you catch an out-of-spec chamber. Forster is trusted in the gunsmithing community for precision and reliability, and this kit is sized and finished to withstand repeated use on the job.

Key Features

• Three-gauge system covers the full 5.56 NATO headspace range
• Reduced rim and ejector cutout design—no bolt disassembly needed
• Precision-manufactured by Forster for consistent, repeatable results
• Fast field verification of chamber spec on AR-pattern rifles

Specifications

Frequently Asked Questions

Can I use this headspace gauge kit without removing my bolt?

Yes. Forster designed these gauges with a reduced rim and ejector cutout specifically so you can insert and check them without disassembling the bolt. That's a key advantage of this kit.

What do the three different gauge measurements tell me?

The Go gauge (1.4646") is minimum spec. The Midrange gauge (1.4736") is a reference point in the middle of the safe range. The Max Field gauge (1.4868") is the maximum safe limit. Running all three in order tells you exactly where your chamber measures.

Is this kit compatible with all AR-pattern rifles in 5.56?

This kit is designed for 5.56 NATO chambers. If you have questions about compatibility with a specific rifle or upper receiver, we recommend consulting the rifle manufacturer or a qualified gunsmith.