DONT do the pound on a socket method. Just grind them out with the dremel. Trust me, the pound method DOES NOT work 
Yea... I read some horror stories of the tube getting so out of round or expanded that the barrel and magazine cap would not go back on.DONT do the pound on a socket method. Just grind them out with the dremel. Trust me, the pound method DOES NOT work![]()
About how big of a hole do you have in the tube now? Do you have any problems with shells or the follower hangin up?I tried the pound method. I just couldn't get it to pound out smoothly. So, I drilled that sucker and sanded. 100% dy-no-mite! No problems at all.
Saw that link too... Seems like it may be the safest option but will take longer without all the materials together.Just take a piece of steel barstock, and put a taper on the end. Radius all the edges so there's little to no chance to scratch the tube. Make it so it could also be used as a mandrel to peen the dent out from the outside.
This guy's idea looks pretty good too.
Removing Dimples on Remington 870 Magazine Tube | Rem870.com
Maybe a combination of the 2 with a specially modified C-clamp.