Firstly, I was saying the opposite and I think at least one other agrees that the last person I would trust in this case to produce an un-biased opinion would be Walther.
Secondly, a base metal comparison will prove what exactly? given that we would expect that if the gun IS genuine that it came from an early batch which will have been cast at a different time, possibly from a different supplier unless Walther had their own foundry and potentialy with a different base metal specification (which may have been rejected).
I think that the method of manufacture and and the marks that the machinery that produced it needs to be the point of focus - all difficult to fake.
Don't forget Walther say they never made one - so they won't be of any help at all.
I'm no expert on the finer details of the model, however the author of this article seems to have done quite a bit of research on the LP53 and this seems to indicate that the earliest one he has found has been done on a engraving machine.
It might be the photos of course, but while you're looking - compare the two finishes around the markings on these 2 guns as well - they appear quite different and their authenticity is not in doubt...see below:
http://www.network54.com/Forum/40594...il+pics+added)