I recently repaired a pump shotgun part for my nephew. One piece was a steel tube, the other a pressed (sintered?) steel block with a stepped hole to receive the tube. The assembly was originally soldered(furnace brazed?), though after cleaning there was very little evidence of any solder, hence the failure. After cleaning with a spray, non-chlorinated solvent, the repair looked simple enough. Just a careful micro-type weld around the joint where the tube entered the block. I knew the porous nature of the pressed metal might be a problem, and it was. I did manage three small stitch welds around the tube, but not as pretty as I would have liked. Oil would ooze out of the metal causing sparkles and destroying the tip of the tungsten.

I used DC TIG, 1/16" Thor. tungsten, 55-60amp max foot pedal control, no pulse, and .030" steel mig fill wire. I doubt if silicone bronze fill would have worked any better.

Any ideas as to how to clean this pressed metal part without destroying the gun blue finish, that would have allowed a cleaner weld?