did armorers check head gap?

[cswaffie]

How often , if ever, did armorers check head gap on Enfields? By head gap, I mean the distance between the bolt face and the rim face when a case was seated in the chamber.

Also, how important was the shoulder seating against the shoulder in the chamber when dealing with head space? I always thought head space was measured at the rim.

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[Alan de Enfield]

Also, how important was the shoulder seating against the shoulder in the chamber when dealing with head space? I always thought head space was measured at the rim.

On a 303 Rimmed cartridge the shoulder does not seat against the chamber 'shoulder'. The cartridge rim seats in the rear of the chamber.

The headspace is measured with headspace gauges that simulate the rim of the cartridge.
The cartridge rim specification is 0.064" max and 0.054" minimum.
The headspace gauge is 0.064" minimum (the same as the max cartridge rim dimension) and 0.074" maximum (which allows for 'wear & tear')

If you have a 0.064" thick cartridge rim and a 0.074" headspace then there is an additional 0.010 (10 thou) 'sloppiness', if however you are using some of the American made brass which tends to be on the thin side you could have a rim thickness of 0.057" and with a headspace of 0.074" have an additional 'slop factor' of 0.017" (17 thou)

It is this 'slop' that we try to tighten up by using larger (longer) bolt heads and reduce the EFFECTIVE headspace - however if you adjust your headspace to minimum for Rem, Win brass etc (example 0.057" rim) and then try and use Military surplus, HXP or Prvi cases (0.060"-0.064") you will struggle to close your bolt due to the increased rim thickness.

[cswaffie]

f you have a 0.064" thick cartridge rim and a 0.074" headspace then there is an additional 0.010 (10 thou) 'sloppiness', if however you are using some of the American made brass which tends to be on the thin side you could have a rim thickness of 0.057" and with a headspace of 0.074" have an additional 'slop factor' of 0.017" (17 thou)

It is this 'slop' that we try to tighten up by using larger (longer) bolt heads and reduce the EFFECTIVE headspace - however if you adjust your headspace to minimum for Rem, Win brass etc (example 0.057" rim) and then try and use Military surplus, HXP or Prvi cases (0.060"-0.064") you will struggle to close your bolt due to the increased rim thickness.

Yes, Alan, that's it. How did they gauge that slop/space?

If you throw in a headspace gauge, it measures if the bolt will close on certain rim thickness. So, if you then put in a case with a thinner rim, is it out of spec? There's a gap there.

How'd they measure that gap - or did they at all (my original query). Or, was it just considered in spec and not bothered with?

[Peter Laidler]

Did Armourers check the headspace........? They very certainly did. On EVERY weapon in their charge at least once a year during the annual PRE inspection and at any other between time when deemed necessary.

[Alan de Enfield]

"They" would not be using a variety of case rim thicknesses (well they would but the Mil spec is generally thicker than the commercial ones) so it was not an isue.

If the bolt closed on a 0.064" headspace gauge and did not close on a 0.074" gauge the rifle was safe, within specification and was 'passed'

[Beerhunter]

Also, how important was the shoulder seating against the shoulder in the chamber when dealing with head space? I always thought head space was measured at the rim.

As has been alluded to, not with a rimmed cartridge like the .303.

[Son]

One comment I would like to make to maybe add a little perspective ...

quite likely almost EVERY Lee Enfield Rifle (except for DP rifles) didn't have any issues with headspace until SAAMI wrote their own spec for brass and disregarded the OEM's specifications.

Use the correct gauge to check headspace .074"... if it passes the gauge and your brass is failing, then it is (almost certainly) your brass at fault. It will be thinner in the rim, lighter in the base and usually thinner in the walls too than the ammunition originally intended for use in these rifles