tw, that's an interesting point too. I know someone who had some rather old and soiled 8mm. Mauser military stuff and put it in a case tumbler to 'shine' up the rounds for a bit. Result was a well blown action and split stock. The reason being that the tumbling had ground up the powder causing it to burn a lot quicker. Very dangerous practice. I should think that it would take quite a bit though to get it that way. Lagopus.....