I punch lots of rivets in a session, so they force themselves out; any that are stuck I just push up the tube using a cocktail stick or piece of florist wire.
Just the opposite of my experience; I had them clog the tube, and the force required to push them out bent and tore them. I suppose I shall have to figure how to lubricate the process...
*heh heh, heh heh* I said 'lubricate'.
Doug