Just read the "my 45 set up...." post and it occurred to me some forum members may be able to set me straight. Once in a while I get a piece of brass that won't slide into the shellholder. No big deal, lots more to reload. My experience that prompts this post is with 30 carbine USA headstamp brass. I've learned that any brand of 30 carbine brass grows. I have to trim 12 to 15 % of my resized 30 brass, regardless of HS, every time I prep cases.
I prime with a Lee Bench primer, the one that uses special, can't be used for anything else, shellholders. I've noticed one out of ten pieces of USA 30 brass won't fit into the shellholder. I pitch those but next time I'm priming there are more that won't fit, even though they fit last time.
I believe this particular shellholder is machined to fit pretty tight. But I've never had any other brand of brass (LC, Starline, Remington, Winchester, etc.) fail to slide into the holder & some have been reloaded 8 or 10 times. I should add that these are mild loads, at 13.7 grains 4227, easily a full grain below max, meant to reduce wear & tear on my firearms.
I always assumed brass growth occurred in the case wall. But I think in this brand the extractor groove is either getting tighter or growing forward from the rim.
So has anyone out there ever investigated where brass growth occurs, particularly in a slightly tapered case? Or why else would cases that fit the last time primed not fit again?