I have some Remington 6.5x55 cases that have developed some black streaking (about 1/4 of the case). I have tried removing the streaks with tumbling, steel wool, vinegar, and mineral spirits with no success. Does anyone else have this problem? What is the cause and does it indicate anything like a defective case??
TIA

Re: "What is the cause and does it indicate anything like a defective case??" Hard to judge without seeing but my only concern would be whether some of the zinc has leached out of the brass where the streaks are located. The principal cause of that would be having the cases exposed to chemicals, such as ammonia, which would do this and weaken the brass. Still, I wouldn't be too concerned unless the streaks extend into the head and web area.

BEJ,

I would be concerned that these are cracks. If you can't remove them from polishing the SURFACE, there is a chance it could be a crack. I would:
1)Look at them under some magnification and bright light.
2)Carefully probe the area by dragging a sharp pointed, hard object over the area to see if it "catches."
3)Cut one apart in the middle of the suspect area and see if it is weak or split in that area.

Maybe I'm being a little anal here, but it seems prudent to me to take a bit of time to prevent a possible ugly situation.

My $.02 -