Was neck sizing some 30/40 yesterday and had done 50 when I noticed one that looked a bit iffy. Grabbed another from my box of spares and when I sized it there was scoring on the neck. Not a scratch, scoring was over an 1/8 inch wide. The spare case was clean so I don't know what would cause this. Tried scrubbing it out with brake kleen and a 30 caliber brush and that helped but still leave a slight mark and a very faint scratch on the case neck. Wondering if 0000 steel wool and oil on a brush and spinning it with a drill would clean it up without damage to the die? All else fails will bite the bullet and replace it.