sks ejecting very dirty brass

[u/Spiritual_Rope_6952]

i have a chinese sks, cosmoline all cleaned up, but when i shoot it (norinco non-corrosive) the cartridges come out all dirty with some kind of soot all over them. is that normal? otherwise it works perfectly and ive never had a jam. ive just never seen a semi auto ejecting brass so dirty before

[u/NemrahG]

Steel cases don’t seal as well as brass, so you end up getting gas leaking around it making it dirty. Also, they’re just copper plated, like a .22lr, so it’s pretty easy to scratch off the finish.