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" is the critical 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 negatively impact accuracy. For example, unsupported brass fired in a rifle with excessive headspace can rupture, causing gas to blow rearward with dangerous force, much like rocket exhaust. With safety on the line, Forster Headspace Gages are carefully manufactured to precise standards, ensuring accurate chamber testing. If a rifle closes on a FIELD gage, it means the chamber is dangerously close to or already exceeds the SAAMI specified maximum chamber size, emphasizing the importance of proper headspace for both safety and performance.