Every gunsmith understands that the proper use of a headspace gage is the most reliable method to test the length of a rifle chamber. "Headspace" refers to the distance between the face of the breech and the base of the cartridge when the action is closed. Excessive headspace can not only impair accuracy but also pose a significant safety risk. For example, unsupported brass fired in a rifle with excessive headspace can rupture, sending gas rearward with explosive force, similar to rocket exhaust. Because your safety is Paramount, Forster Headspace Gages are crafted with meticulous care and strict manufacturing standards to ensure precise testing of your rifle's chamber. If a rifle closes on a FIELD gage, it indicates that the chamber is dangerously close to or has already exceeded the SAAMI specified maximum chamber size, underscoring the importance of maintaining correct headspace for both safety and optimal firearm performance.