At the range yesterday, my newly aquired Makarov experienced about 6 "stovepipes" in 150 rounds ( various ammo). Upon examining the fired brass, it is clear to me the problem is a very rough and tight chamber, causing the extractor to periodically slip from the fired brass. What have you guys used to polish up chambers. I've used a Dremel with Mothers Mag or Flitz, but I need something a bit more aggressive. What say you ??