• 5.56 NATO CHAMBER HEADSPACE GAGE: The proper use of Headspace Gages is the most reliable way to test rifle chamber length. The 5.56 NATO maximum chambering requires a slightly longer headspace than the commercial 223 cal. Rem.
• GO/MINIMUM LENGTH: 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. NATO Minimum rifle chamber gages check to see that the rifle will accept the longest (headspace dimension) NATO ammunition cases that are currently manufactured.
• MAXIMUM LENGTH: The Forster NATO Maximum rifle chamber gage checks to see that the rifle does not have excessive headspace, which could lead to dangerous pressure problems. The NATO Maximum Headspace Gage measures 1.6455"
• 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 Gage 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 gage, and the gun’s actual chamber length , when the head of the cartridge is flush against the bolt face.