Product Overview
Every gunsmith knows that proper use of a headspace Gauge 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 Gauges 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 Gauge, the rifle chamber will accept any ammunition that is made within SAAMI (industry standard) specifications. If a rifle closes on a NOGO Gauge, 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 Gauge, the rifle chamber is dangerously close to or already over the SAAMI specified maximum chamber size.
- 257 ROBERTS: Use to check headspace of 257 Roberts, 6.5×257 Roberts, & 7mm Mauser (7×57)
- RIMLESS CARTRIDGE HEADSPACE: The proper use of Headspace Gauges 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.
- FIELD: FIELD Gauges are slightly shorter than the SAAMI maximum in order to give a small safety margin. If a rifle closes on a FIELD Gauge, its chamber is dangerously close to, or longer than, SAAMI-specified maximum chamber size. If chamber headspace is excessive, the gun should be taken out of service until it has been inspected and repaired by a competent gunsmith.
- 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 Gauge thoroughly inspected with NIST-certified measurement tools to ensure the highest quality product.
- MEASURING MEANINGFUL HEADSPACE: Properly speaking, and for safety purposes, one measures “headspace” as the difference between the length of a standard cartridge, as represented by a Gauge, and the gun’s actual chamber length , when the head of the cartridge is flush against the bolt face.
