. If the number stamped there is 0, 1 or 2 you will be able to adjust the headspace by simply removing (unscrewing) the bolt If this is so, you might want to tighten up the headspace. It has been predetermined and accepted by the industry as a given length. 2. rim thickness R is 1.63 mm; min barrel relief R is also 1.63 mm. Top subscription boxes – right to your door, © 1996-2020, Amazon.com, Inc. or its affiliates. The NO-GO gage is a valuable tool for gunsmiths’ reaming new chambers, in order to ensure tight and accurate headspace. Rimless cases use the distance measured from the bolt face to the middle of the shoulder to determine headspace. NO-GO: Corresponds to the maximum headspace we recommend for gunsmiths’ chambering new bolt-action rifles. ... 303 … “Headspace” is the distance between the face of the breech and the base of the cartridge when the action is closed, and excessive headspace … when they hold a fired case up beside an unfired one. Headspace is measured differently depending on whether the firearm’s caliber uses rimmed, belted, or rimless cartridges. A THIRD STANDARD?? The gauges are … 7.62 x 39 mm Russian. } If a rifle closes on a FIELD gage, its chamber is dangerously close to, or longer than, SAAMI-specified maximum chamber size. I said most - not all. Reloading the 303 British: Chambers and Headspace,
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