Winchester 34gr Lubalax factory ammo.
Few weeks ago i was doing some shooting, between round 10 and 15 i noticed that the round chambered a little tight "case on right". I fired it and all was fine, but when i removed it from the chamber I noticed something black on the shoulder. Without thinking i touched it and in the grass it went. Took a patch and ran it in the chamber and it wasn't really dirty.
The second round, on the left, was a few weeks later. This one chambered fine, but upon firing it felt "HOT". Shooting about 6" higher at 350 yards.
I compared the primers of the rest of my brass and they all look the same.
Any ideas?

