Forster Headspace Gage 204 Ruger - Go

Headspace standards are set by SAAMI (Sporting Arms and Ammunition Manufacturers Institute) specifications. Headspace is measured from the bolt face to one of four locations: #1 measurement is taken from the top of the rim of rimmed cases like the .30-30 #2 measurement of the shoulder of a necked case like the .30-06 #3 measurement of the case mouth on a straight or tapered case like the 30 Carbine #4 measurement of the belt of a belted case like the .300 Winchester Magnum. Headspace gages are available in three different lengths, listed below, from shortest to longest: Go Gage: Go Gages match the minimum chamber dimensions allowable under SAAMI specifications. In order to accept SAAMI maximum ammunition, the rifle must be able to chamber the correct go gage. No-Go Gage: No-Go Gages are sized to the maximum recommended headspace dimensions. If a rifle will chamber the no-go gage, it may still be within specifications, or this could indicate excessive headspace. To determine if the rifle is safe to shoot, the chamber must be checked with the field gage. Field Gage: Field Gages correspond to the maximum safe headspace dimension. If a rifle will chamber a field gage, it should be inspected and repaired by a competent gunsmith prior to use.