What type of sandpaper to remove rustspots?

[saxman]

Alex; There are some things you need to do.
*Get a good magazine, preferably from the correct period, but any quality mag should function.
*Get a book or download instructions for taking apart, putting together and operating.
*When you get the pistol, take it to a good gunsmith for a cleaning, oiling and evaluation. You may want to carefully remove the wood stocks and look under them for rust. For the spots you have mentioned and any others you may find, just wipe them with an oily patch for now. Tell the gunsmith not to buff, polish or do anything else to the gun's finish or try to remove rust without clearing the method with you first.
*Use the methods described by the others to deal with rust. I have taken #0000 steel wool, dry, and deliberately tried to remove factory blue, and it's nearly impossible. Like they said, use a light, penetrating gun oil and very light pressure. Sometimes the rust will leave a dark spot in the blueing - this may be permanent without stronger meausures that may damage the blue.
*You need to preserve the stocks, as they must be very dry after all those years. There are many opinions on how to do this, and here's another; use no water at any time. Take them off the pistol and clean them with dry cleaning fluid (naptha) on a toothbrush. Check for cracks and repair by filling crack with liquid (not gel) Super glue. Oil the stocks with raw (not boiled) linseed oil.
*Get some standard round-nose ball ammunition.
*You should now be ready to fire it, assuming the gunsmith okayed it.
You are going to own a beautiful, valuble Luger, and you you're getting a legendary buy on it. Enjoy.