The last dent I repaired was a magazine tube for a Winchester Model 12.
I've got a ding in a M12 16 gauge mag tube as well. Flimsy tube in comparison with the rest of the gun. Gil
If you lived near by I would machine a set of plugs for you. My advice is to find a good lathe man and have him machine a set for you. Use increasing size increments till you can get a plug through .001 smaller than the ID of the tube. Position that one over the dent and finish up by peening it with a soft mallet made of lead. Works for me.
