I've been reloading PPU brass for about four years now, and I'm very pleased with the way it has been holding up.
I'm now on my fifth reloading of a fairly moderate 7.5x55 load. I'm not going to post details here, but it's one of those posted by carlos diaopter over on swissrifles.com, where we are both contributors. It has shown no signs of any excess pressure. I also full-length resize after every firing for both K11 and K31.
Grafs' brass is the same deal, as it should be, since I'm told it's also made by PPU.
tac
swissrifles.com