The Forster 6.5 Grendel Headspace Gauge, NO-GO (brand part no. HG65GRENN) helps builders confirm a 6.5 Grendel upper is safe to fire, whether it’s a factory barrel or a custom build. Headspace is the distance between the face of the breech and the base of a chambered cartridge, and it is one of the most safety-critical measurements on any rifle. Excessive headspace lets brass stretch or rupture on firing, which can send gas blasting rearward toward the shooter, so gunsmiths rely on precision gauges rather than guesswork to verify a chamber is cut correctly. Forster extends that same manufacturing precision into its 6.5 Grendel gauge line.

Key Specifications

• Ground as a NO-GO gauge to flag excessive headspace in a 6.5 Grendel chamber.
• Precision length of 1.34 inches for a consistent, repeatable test.
• Supplied as a single gauge dedicated to the 6.5 Grendel cartridge, a common AR-15 platform chambering.
• Weighs approximately 0.07 pounds, light enough to carry in a range bag or tool kit.

Frequently Asked Questions

What does it mean if the bolt closes on this NO-GO gauge? If the rifle’s bolt closes on a GO gauge, the chamber will safely accept ammunition built to SAAMI industry-standard dimensions. If the bolt closes on a NO-GO gauge, the chamber may already have excessive headspace, and if it closes on a FIELD gauge the chamber is dangerously close to, or already beyond, the maximum SAAMI-specified size. Most gunsmiths aim to keep a chamber cut somewhere between the GO and NO-GO dimensions.

Should AR-platform 6.5 Grendel builders check headspace? Yes, verifying headspace is just as important on an AR-pattern upper as it is on a bolt gun, especially with a custom barrel or headspace-adjustable barrel nut.

Buy the Forster 6.5 Grendel Headspace Gauge, NO-GO

Verify your 6.5 Grendel upper before it sees a live round. Shop this gauge in our rifle accessories selection, and our Lubbock, Texas team will get it shipped quickly.