Forster 5.56 NATO Headspace Gage Maximum Chamber 1.4736 +0/-.0003

Headspace Gage Features Because your safety is on the line Forster Headspace Gages are made with painstaking care and exacting manufacturing standards to ensure accurate testing of your rifle s chamber. If a rifle closes on a GO gage the rifle chamber will accept any ammunition that is made within S.A.A.M.I. (industry standard) specifications. If a rifle closes on a NO GO gage the rifle chamber might have excessive headspace. Most gunsmiths chamber a rifles headspace between the GO and NO GO dimensions. If a rifle closes on a FIELD gage the rifle chamber is dangerously close to or already over the S.A.A.M.I. specified maximum chamber size. Headspace Gage Specifications .223 Remington S.A.A.M.I. 1.4736 plus zero minus .0003 Maximum chamber