While I normally agree on solid research, sometimes you come across an item (guns in our case) that you know has some value.
I did that with a Luger recently, bought it before solid research and its proven to be far more valuable than what I bought if for.
The best place to get the gun assessed is the CMP forum. John Beard and Rick the Librarian are two of the top people there but others will chime in and pick out the details.
The group will look at a gun, discuss it and usually ultimately concur on its authenticity. There is spirited discussion at times.
Value wise that's a terribly tough one. Most of the experts are lagging behind what the guns are going at in auctions. Ultimately a fake will bite someone. You want to be sure its not you.
A guy on the Lugger forum bought into one of the fakes and lost 20k. So this is not costly territory (and my Luger purchase was not even close to up there) Gun will always have a value of $600 or better as a shooter so the difference may be only a few hundred dollars loss at worst.
Contrary to the following, the box and papers can have value, I have an A3 with provenance and its worth more than an A3 without it. Often that adds significantly to the value and its authenticity. By itself, no, but combined the two and the connection confirm each other.
well the box and any papers that it came with are probably worthless as these were all sold as military surplus at any store you could possibly imagine at that period anyway.