I sacrificed an old small C clamp, filed the upper jaw until it was thinner and rounded to roughly match the inside of the magazine tube. This took about 15 minutes?, then using a thin piece of wood on the outside to protect the exterior of the magtube,cranked it tight.
It eventually moved the dimples out enough to be able to lightly tap in a socket(think it was a 17mm deep socket)that fit snugly into the tube.
Once the socket got past the dimples, then tapped the outside carefully with a hammer to really flatten it out and keep a nice round shape. A little tiny bit of light filing on the outside so the barrel ring would slide over an it works perfectly. Used cold blue on the lightly filed areas. This way, very smooth no holes in the mag tube, very little material removed at all.
Also, after removing those dimples, and using S and J's new follower but with the original mag tube cap, I am now able to fit 6 in the stock tube, and 7 with the +2 adapter.