Lugerdoc,
We have a "sanitized" letter at this URL in our General Information link on the Lugerforum homepage that is a reply by the ATF to an inquiry about just such reproductions...
According to this letter, a "original" luger (i.e., a Luger for which a stock was originally produced and would be exempted from the NFA if used with an original stock) is used with a reproduction stock that closely approximates the original stock is legal...
Here is the URL:
BATF Letter on the use of reproduction shourlder stocks with Lugers
and here is the pertinent text from the letter for those who don't want to leave this message thread...
</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">
Our Firearms Classification Panel has examined your request and is their opinion that the above mentioned pistols equipped with currently made reproduction shoulder stocks which either duplicate or closely approximate the dimensions and configuration of the original stocks would also be primarily of interest to collectors and not likely be used as weapons. Therefore, any Luger or Browning Hi-Power pistol which would be removed from the purview of the NFA if equipped with an original shoulder stock, would also not be subject to the NFA is equipped with a reproduction shoulder stock which either duplicates or closely approximates the dimensions and configuration of the original stock.
It must be pointed out that should one of the subject reproduction stocks be attached to any handgun which has not been specifically removed from the purview of the NFA with an original stock, the combination would be subject to all of the registration and transfer provisions of the NFA. </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">