Re: Primer pockets expanding. Pressure sign?
Interesting...I have reloaded Federal brass in 243, FL sizing, up to 8 times with mostly non-max charges level that results in medium velocity yet flattened primers (no other pressure signs) and yes some primer pockets are getting very easy. I've recently had a few cases that started to rupture horizontally about 1/2" up from the case head. But this is after 8+ reloads.
I have noticed that Winchester brass seems to take more of a beating out of an autoloader than Remmington, making me think it is softer.