Hi Walt,
Itâ??s actually fairly easy to tell if the crest has been ground off. Look at the front of the barrel extension where the barrel is screwed into the barrel extension. The front of the barrel extension should be round. If anything has been removed from the top of the barrel extension (the area we have been calling the â??chamberâ?) the top of the barrel extension will be flattened due to the removal of material. If in doubt, compare it to your other Lugers (assuming they are not 1920â??s production!).
On a (very loosely) related subject, my shooter Artillery is a FrankenLuger (a Luger made up from parts scavenged from dead Lugers) and has the barrel extension from a Portuguese Luger. Iâ??ll attach a photo - you might want to compare the Portuguese proof/acceptance stamp on my Luger to those on your Luger.
Hope this helps.
Best regards
Kyrie
http://boards.rennlist.com/upload/FrankenArty.jpg