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Kyrie · 02-13-2019, 06:33 AM

Rick,

US arms/ammunition manufactures compliance with SAAMI is legally voluntary. The US, unlike most EU countries, has no set of proof laws and no government established and run proof houses.

Generally speaking, those (mostly European) countries that are signatories to the C.I.P. agreement have internal laws that require, by statute, adherence to C.I.P. standards as a prerequisite for any firearm/munition to be legally offered for sale in commerce (sometimes including export - even export to countries that are not C.I.P. signatories)

On the subject of head space gauges and how vendors mark them, vendors can do just about anything they want. Ultimately it's up to the people who need to use to head space gauges to understand what the gauges measure, and to understand and appreciate the potential problems of firing SAAMI compliant ammunition in a chamber that is not SAAMI compliant (e.g. chamber is too short as revealed by failing to close on a GO gauge, or chamber is too long as indicated by closing on a FIELD REJECT gauge).

The NO GO head space gauge has some arbitrary length between the lengths of the min (GO) and max (FIELD REJECT) lengths of a chamber. It is really only useful for hobbyist reloaders who reuses fired cases, and especially the hobbyist who intends to reload a fired case more than once.

Reloaded ammunition that is intended for use in a firearm that passes a FIELD REJECT gauge but fails a NO GO gauge should be neck sized only and never, ever full length resized. Full length resizing a case progressively thins the cartridge case wall (esp. the case wall just ahead of the case web). This thinning of the case wall progressively, with each incident of full length resizing, increases the potential for a catastrophic case failure that dumps the chamber pressure out of the firearm's barrel into the slide and frame of the firearm. That's how people lose fingers, or hands, or for the very unlucky their lives.

A chamber that has distal end of the head space datum line beyond that length expressed by a NO GO gauge significantly increases the risk of case failure with reused cartridge case, and greatly increases the risk of case failure for cartridge cases that have been full length resized.

The intersection of chamber head space, cartridge case length relative to the head space datum line, the effects of chamber pressure on the cartridge case of a round of ammunition when that round is fired, and the reuse of cartridge cases is a profoundly complicated discussion. The above comments only scratches the surface of that discussion and should be read with the understanding it's a small part of a much larger subject.

02-13-2019, 06:33 AM	#23
Kyrie User Join Date: Jun 2002 Posts: 757 Thanks: 0 Thanked 212 Times in 101 Posts	Rick, US arms/ammunition manufactures compliance with SAAMI is legally voluntary. The US, unlike most EU countries, has no set of proof laws and no government established and run proof houses. Generally speaking, those (mostly European) countries that are signatories to the C.I.P. agreement have internal laws that require, by statute, adherence to C.I.P. standards as a prerequisite for any firearm/munition to be legally offered for sale in commerce (sometimes including export - even export to countries that are not C.I.P. signatories) On the subject of head space gauges and how vendors mark them, vendors can do just about anything they want. Ultimately it's up to the people who need to use to head space gauges to understand what the gauges measure, and to understand and appreciate the potential problems of firing SAAMI compliant ammunition in a chamber that is not SAAMI compliant (e.g. chamber is too short as revealed by failing to close on a GO gauge, or chamber is too long as indicated by closing on a FIELD REJECT gauge). The NO GO head space gauge has some arbitrary length between the lengths of the min (GO) and max (FIELD REJECT) lengths of a chamber. It is really only useful for hobbyist reloaders who reuses fired cases, and especially the hobbyist who intends to reload a fired case more than once. Reloaded ammunition that is intended for use in a firearm that passes a FIELD REJECT gauge but fails a NO GO gauge should be neck sized only and never, ever full length resized. Full length resizing a case progressively thins the cartridge case wall (esp. the case wall just ahead of the case web). This thinning of the case wall progressively, with each incident of full length resizing, increases the potential for a catastrophic case failure that dumps the chamber pressure out of the firearm's barrel into the slide and frame of the firearm. That's how people lose fingers, or hands, or for the very unlucky their lives. A chamber that has distal end of the head space datum line beyond that length expressed by a NO GO gauge significantly increases the risk of case failure with reused cartridge case, and greatly increases the risk of case failure for cartridge cases that have been full length resized. The intersection of chamber head space, cartridge case length relative to the head space datum line, the effects of chamber pressure on the cartridge case of a round of ammunition when that round is fired, and the reuse of cartridge cases is a profoundly complicated discussion. The above comments only scratches the surface of that discussion and should be read with the understanding it's a small part of a much larger subject.