308 Winchester Headspace Gauge Set GO and NO-GO

Every gunsmith knows that proper use of a headspace gage is the most reliable way to test the length of a rifle chamber. “Headspace” is the distance between the face of the breech and the base of the cartridge when the action is closed, and excessive headspace can be dangerous as well as impair accuracy. For instance, unsupported brass fired in a rifle action with excessive headspace can rupture, allowing gas to blow rearward like rocket exhaust. Because your safety is on the line, Forster Headspace Gages are made with painstaking care and exacting manufacturing standards to ensure accurate testing of your rifle’s chamber. If a rifle closes on a GO gage, the rifle chamber will accept any ammunition that is made within SAAMI (industry standard) specifications. If a rifle closes on a NOGO gage, the rifle chamber might have excessive headspace. Most gunsmiths chamber a rifle’s headspace between the GO and NOGO dimensions. If a rifle closes on a FIELD gage, the rifle chamber is dangerously close to or already over the SAAMI specified maximum chamber size.

• 243 WIN: Use to check headspace of 243 Win., 260 Rem., 7mm-08, 308 Win., 338 Fed, & 358 Win.
• RIMLESS CARTRIDGE HEADSPACE: The proper use of Headspace Gages is the most reliable way to test rifle chamber length. Headspace in a rimless cartridge is the distance between the bolt face and a datum line, determined by SAAMI, where the front of the cartridge rests on its shoulder when the bolt is closed.
• NO-GO: Corresponds to the maximum headspace we recommend for gunsmiths’ chambering new bolt-action rifles. This is not a SAAMI-maximum measurement. If a rifle closes on a NO-GO gage, it may still be within SAAMI specifications, or it may have excessive headspace. To determine if there is excessive headspace, the chamber should then be checked with a FIELD gage. The NO-GO gage is a valuable tool for gunsmiths’ reaming new chambers, in order to ensure tight and accurate headspace
• GO: Corresponds to the minimum chamber dimensions. If a rifle closes on a GO gage, the chamber will accept ammunition that is made to SAAMI maximum specifications. The GO gage is essential for checking a newly-reamed chamber in order to ensure a tight, accurate, and safe chamber that will accept SAAMI maximum ammo.
• PRECISION MACHINED: Manufactured from top-quality, hardened steel and precision ground to ANSI and SAAMI tolerances. Headspace tolerance ground to a very exacting ±.00015. Each Headspace Gage thoroughly inspected with NIST-certified measurement tools to ensure the highest quality product.