I recently had a local 'smith assemble a rifle for me with my chosen parts. The action is an FN SPR, the barrel a Shilen match grade stainless select blank which he turned and chambered in .308 for me.
I purchased 2 boxes of ammo to break it in and begin the process of tuning a load for the rifle with the spent brass. I've read before how one member is adamant about checking the length of an unfired round before firing to provide a "measurement" if you will, of the effect the chamber has upon the casing. Well, the measurements were all over the place. From 1.623 to 1.64 prior to firing checked with a Hornady headspace comparator gauge.
After the firing, the brass is, for the most part, shorter
But, all fall within .0005 of each other(1.624-1.6235(guessing at the .0005 as its halfway at least between the 3 and 4)).
My question is wouldn't the firing "stretch" the cases to form the chamber dimensions? And if too small(the chambers headspace) wouldn't there be indications of excessive pressure?