Manuel -
Please post some pics of your P-38. I also have a P-38 (as do most members here); it is a Russian capture/VoPo refurb. Mine was 'dipped' to refinish it. This is different from what your local re-bluer would do, as it was not buffed (no reason to). Mine was lightly 'dipped'; there have been reports/complaints here of a tar-like coating on some Lugers/P-38's refurbed by the Eastern Bloc rebuilding facilities, but mine is very nicely done. Some numbers have been XX'd out and new numbers stamped ("force matched" is the term used here).
As John mentioned above, the P-38 Forum [
http://www.p38forum.com/] is a good source of information; Jan Still's site [
http://luger.gunboards.com/index.php] is good as well. There is also the Walther Forum [
http://www.waltherforums.com/forum/] which is another good site for enthusiasts.