Sorry to be tardy on my reply, this is going to sound a little cave man but it worked. I had a brass rod about 1/4 thick two inches longer than the mag tube and threaded on the end. i took several washers and turned them down to just barely fit in the tube and attached them to the threaded brass rod with a nut. (it vaguely looked like a cannon ram rod.) then i whacked the end of the brass rod on the floor and forced the rod with the washers through the tube. i used a progressively larger and larger washers attached to the end of the brass rod and it pushed all the dents out. the tube works fine now. simple, crude but it worked