First impressions - it's a little rough, but I'm happy! This thing is not new by any stretch of the imagination, but overall the metal seems in good condition - needs a really good cleaning and oiling/greasing.
Pics will be added below.
I have a 1939 with manufacturer code 42. So manufacturer is Mauser-Werke AG, Oberndorf a./N, early code. I actually requested a 1939 and Wideners obliged! Keep that in mind - they may have others in better shape, but I wanted a 1939 rifle.
The camera tends to make the finish look worse than it is in person. It's got a sort of "frosty" speckled look to the finish, but the metal is smooth.
There is some corrosion in places, but not excessive for a rifle so old that saw battle, most likely.
Bore is frosty inside, but I need to clean it thoroughly to see the real condition. The rifling is a bit worn, but again this is a 1939 rifle - no idea how often this was fired in battle or afterwards before being stored.
Nazi markings are stamped all over. As others have noted, there are stamps all over the place - serial numbers do not seem to match except for receiver and barrel, and the stock has a matching number stamped into it (could have been done by the Russians?). Stock is cracked on one side of the shoulder only. Stock appears laminate, and has some sort of coating on it that looks like it's been lightly scraped off in places.