Say you want to check your Mauser Headspace

[Aughnanure]

Andrew,

I stands corrected, but a lot of improved cases around here have the shoulder moved forward more than the headspace allowance.

For example one could keep moving the shoulder forward in a 30/06 until there was no shoulder left and still not get a seperated case if the head was against the bolt face on firing.Certainly the striker drives the case forward a bit but not all that much.

If I want to check headspace, which is rarely, I just put some paper between the bolt and the head and measure it when the bolt starts to offer resistance. I haven't owned a gauge for 30 years except a few that I made of brass.

I cannot recall ever seeing a seperated case in a Lee-Enfield that was due to excess headspace.

[andrew375]

Andrew,

For example one could keep moving the shoulder forward in a 30/06 until there was no shoulder left

Then it would not be an "Improved" chamber but a simple wildcat that couldn't be used with factory ammo. The reason why a rimless round will fire even when the apparent headspace is excessive is due to the extractor holding the case head in position. Just ask anyone who has fired .308win in a .30-06, or .270 even.

I've seen many case head separations due to excess headspace, mostly SMLEs and No.4s either fitted with the wrong bolt head, incorrectly fitted barrel or worn receiver shoulders; worn out clunkers condemned by the military inspectors (and sold as such) but then "arsenal reconditioned" for sale to the gullible.