Kuduae, you are correct that the cartridge headspaces on the rim not the shoulder, however I have three different 256 Mannlichers and all have between 0.014" and 0.018" headspace which invariably leads to head seperation especially if using Kynoch factory ammunition as it has a wall thickness of about 0.010" thinner than most other brass.

If reloading unless the die is set so that upon sizing the case the shoulder remains to do the headspacing rather than the rim you will have very short case life and/or case splitting.

I have measured headspace on two other 256 Mannlichers and they were in the same range as the rest.

I have also measured headspace using Bertram Brass, S&B Brass and factory Military ammunition and the results were the same give or take a thou.

However if the headspace is corrected than there are no head separations or cracks. After firing some Kynoch factory ammunition in a rifle with the correct headspace I cut open a case lengthwise and measured the wall thickness and it hadn't thinned at all at any point.

Matt.