Kevin said:
The part of the case which I feel gets worn down, (or worn out) is the rim. I sort of feel like the rim gets worn down and rounded over, causing it to slip and move in the press's case holder. And since I use a hand primer, the cases with degraded rims slip there as well. Or so it feels like this anyway.
Hi,
Kevin, you've certainly heard the joke from the computer world, "It's not a bug, it's a feature." That's sorta what the wiggleosis in the shell holders is.
A buddy of mine is not an engineer, but worked with them for close to 40 years and can draw pretty convincing pictures. Add that he loads on an old Bonanza, pre-Forster, Co-Ax press which normally doesn't use the style of shell holder we're used to (though I understand the newer ones can be adapted.)
He draws a picture of how the shell holder is supposed to have some wiggle room in there so the case will be able to self center in the various dies. So I don't think rim "wear" (as little as I suspect there is--think about the stories you've heard of .45 ACP cases loaded so many times the head stamp's gone) causes much of a problem.
Now that "several 100s" of an inch may be quite significant when we're talking over all case length. We need to remember that an additional shell length of 0.010" (one hundredth of an inch) in a .30-06 case probably does little to create significantly different pressures, while that same 0.010" could possibly cause measurable differences in "small" cases like the .327. One would have to spend some time with the chronograph doing "before and after" comparisons to see if that argument holds any water.
Rick C