Only ppu ammunition I have used is their 7.62x51 fmj and love it, seriously love it. It shoots very small groups for me. And one flavor of handgun ammunition.
Last year I got injured and wasn't able to do any shooting until new years day. SO I did half a box of 8x57 PPU Thunder and put the rifle away. Aparently the patching I did wasn't enough and now I have patches that come out with that funny reddish brown **** on them, and I can see a spot of black in my barrel I believe is burnt on powder because it seems to be getting smaller as i pull a patched brush through.