Forster Products 30-06 GO & NO-GO Headspace Gauge Set - Compatible with 25-06, 6.5-06, 270 Winchester, 30-06, 8mm-06, 338-06 & 35 Whelen - SAAMI Dimensioned Rimless Hardened Steel Precision Ground - Perfect for Gunsmithing & Firearm Maintenance

Forster Headspace Gages The most reliable means to test rifle chamber length Forster Headspace Gages The most reliable means to test rifle chamber length Smart gunsmiths and shooters have long selected our headspace gages because each is manufactured from top-quality, hardened steel and precision ground to *American National Standards Institute SAAMI tolerances. When safety and performance are on the line, choose our headspace gages and receive the peace of mind that comes with knowing and understanding how to check your rifle’s headspace. *American National Standards Institute, New York, NY, represents and serves the diverse interests of more than 270,000 companies and organizations and 30 million professionals worldwide by promoting and facilitating voluntary consensus standards and conformity assessment systems, and safeguarding their integrity. All of our headspace gages are: Ground to an exacting ±.00015" headspace tolerance to ensure accurate testing of a rifle’s chamber. Carefully inspected with NIST-certified measurement tools. Made with painstaking care and rigorous manufacturing standards. What is Headspace? According to the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI), which sets product standards for firearms and ammunition, headspace is "the distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats." Some shooters are under the misconception that headspace is fixed over the life of the firearm. Headspace can increase after repeated use of ammunition that causes too much pressure. One should routinely check rifle chamber headspace every thousand rounds. Headspace is measured differently depending on whether the firearm’s caliber uses rimmed, belted, or rimless cartridges. What is Headspace? According to the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI), which sets product standards for firearms and ammunition, headspace is "the distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats." Some shooters are under the misconception that headspace is fixed over the life of the firearm. Headspace can increase after repeated use of ammunition that causes too much pressure. One should routinely check rifle chamber headspace every thousand rounds. Headspace is measured differently depending on whether the firearm’s caliber uses rimmed, belted, or rimless cartridges. Rimmed/Belted and Rimless Cartridges Rimmed and Belted Cartridges Headspace = distance between the bolt face and the top of the rim (chamber face) when the bolt is closed Rimless Cartridge Headspace Headspace = 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 Choosing the Correct Headspace Gage Forster Products offers three lengths of headspace gages per rifle caliber. In order from the shortest to longest, they are GO, NO-GO, and FIELD: 1. 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. 2. 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. 3. FIELD: Corresponds to the longest safe headspace. If a rifle closes on a FIELD gage, 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. FIELD gages are slightly shorter than the SAAMI maximum in order to give a small safety margin. Choosing the Correct Headspace Gage Forster Products offers three lengths of headspace gages per rifle caliber. In order from the shortest to longest, they are GO, NO-GO, and FIELD: 1. 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. 2. 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. 3. FIELD: Corresponds to the longest safe headspace. If a rifle closes on a FIELD gage, 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. FIELD gages are slightly shorter than the SAAMI maximum in order to give a small safety margin.