Every gunsmith understands that the proper use of a headspace gage is the most reliable method for testing 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 be both dangerous and detrimental to accuracy. For instance, unsupported brass fired in a rifle with excessive headspace can rupture, allowing gas to blow rearward like rocket exhaust, posing a serious safety risk. Forster Headspace Gages are crafted with meticulous care and precision to ensure accurate testing of your rifle's chamber. If a rifle closes on a GO gage, it confirms that the rifle chamber will safely accept any ammunition made within SAAMI (industry standard) specifications, providing reassurance for both safety and performance.