[John Sabato]

My advice would be to just keep the muzzle/front sight of the barrel in the Kroil. Once every few days, take the barrel and place it on its side with the screwhead up. Support the underside of thefront sight base with an appropriate sized piece of hardwood. Maple hardwood flooring scraps are good for this purpose since they are very hard but won't likely mar the metal surface. You can likely find them in the dumpster where new homes are being built, or the contractor building the home will probably just give you some.

Then take a flat tipped brass punch or drift and place it on the screw head and wallop it with a small ball peen hammer to jar the threads. THEN try to use the tool with moderate pressure... don't try to "KING KONG" wrestle the screw out. Each time you do this, the Kroil will have a new opportunity to get deeper into the threaded connection between the screw and the sight base. Eventually, this screw will move...

With a properly supported front sight base, and judicious use of the hammer and brass drift, this method should not harm your Luger in any way.