I’ve loaded S&B brass for my 7.62X54r and it’s just ok brass. I typically only neck size but that didn’t stop the primer pockets loosening up after 4-5 reloadings. The PPU brass I have for 7.62X54r and 7.5x55 has done much better.
It’s too bad that GP11 is such a pain to reload. I have almost 1000 Bredan primers and the GP11 is top quality brass!! I put it on par with the Lapua stuff I have!