Welcome to the Lugerforum Sandi.
This sounds like a great idea on the surface, but I have feeling that there would be some liability involved that the forum owner might be reluctant to accept, and I would tend to agree with him.
What kind of information do you think would be appropriate for posting other than the gun's description? In the five year history of the forum, I can only remember a few instances where guns were reported stolen. The best suggestion would be a direct interface with law enforcement prior to a purchase.
One problem with Lugers is that for many years, even continuing to today, many folks including law enforcement types don't realize that there is generally a letter suffix to a Luger serial number... but this letter has not been recorded or noticed by the owner, nor does it appear on many types of registration forms where they are required, The result is that there can be quite a few Lugers out there with a four digit serial number... and the date of manufacture and the letter suffix is what distinguishes one from another... So, for example, if a Luger is reported stolen with a serial number of "1234" There could be one out there for every year that Lugers were produced. Even if the letter suffix is recorded as part of the owner's information or on the registration form, or on the stolen gun police report, if the year of manufacture is not recorded, then there is no way to distinguish if a recovered Luger is the correct one, or that one legally possessed is not the stolen Luger. And Lugers were produced during the same years by different manufacturers... another complicating factor.
I also noticed that you didn't include the serial number of the gun you spoke of ????
That is why it is so important that a Luger owner record all the markings and peculiarities about his Luger, and to document it with photographs if at all possible.
Some enterprising entrepreneur might figure out a way to electronically query the NCIC (National Crime Information Center) for a fee, but with the discrepancies described above, there would still be some liability for providing the information to the one paying the fee...
Finally, who's word do you take that the allegedly stolen Luger was legally possessed or owned?
The best way to protect oneself from legal trouble is to require a witnessed bill of sale when a gun changes hands even privately and to record some traceable information about both the seller and the buyer, like photocopies of their drivers licenses. That way if a gun is proven to be stolen, the chain of illegal possession won't start with YOU.
I don't know that there is a workable solution to this problem. Perhaps some of the members could suggest one.
I hope this discussion has been helpful and encourage comments and replies from the membership on this issue.