I'm getting to be convinced that those clearances you mention have more of an effect on brass life than anything else, certainly than pressure (unless we're going way over 70k into "brass plasticity" territory).He's talking about testing for case head expansion that leads to shorter primer pocket life. There are similar tests where measure is compared at the extraction groove, and another at the fired web-line.
He points out that pressure measuring equipment is not actually a final say in this.
And he points out that brass that has yielded, will go right back there (sizing doesn't matter to this).
The useful information is locally measured, and it does not indicate pressure, it's not how to measure pressure, but it can indicate YOUR max load (reloading-wise). People who want their brass to last, measure this stuff. They also look for hard brass alloys, stronger breaches, and lower clearances.
No correlation would be a brain dead joke. What do those studies think is causing the expansion, if not internal case pressure?I've also seen studies that claim no correlation and it's not a reliable indicator of pressure.
Obviously it's pressure. But the idea that you can find a measurement to correlate to a certain amount of pressure is what is in question. Also your dealing with a very small measurement which requires a good micrometer and good technique to get a consistent measurement.No correlation would be a brain dead joke. What do those studies think is causing the expansion, if not internal case pressure?
Exposure to the northern lights? Pixie dust???