I think so. Here are my clues to this -

1. Front sight blade not quite right length (too long)
2. Fonts different barrel-to-frame
3. Bluing different barrel/frame
4. Witness marks don't line up
5. Witness strikes at different angles - two separate strikes

Witness marks, front sight blade can be seen above - bluing & fonts below...

Also - Chamber end of barrel is raw steel; my other Luger (S/42) has blued chamber end of barrel...

I bought a 1939 reprint catalog from Amazon, cheaper, less than $20 (shipping included). It contains lots of information on German commercial guns.

I also ordered a 1928 catalog (reprint). Waiting its arrival.

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The catalog also has a long list of American guns -- Winchester, Remington, Colt, S&W, H&R etc. If you collect American brand names, it has good information. Lots of other stuffs were listed, reloading equipments, gunsmithing tools, lathe, milling machines, cameras (!), etc. etc.

The only exception -- I did not find FN guns inside, which is unfortunate.

Just a WAG, but those are probably Cornell Pubs reprints...they have a bunch listed...

http://www.cornellpubs.com/old-guns/...ic-stoeger.php

Rich,
The barrel crown should be in the white on all rust blue variations. Your S/42 must be made after mid 1937, which is when they started to salt blue everything... small parts which were previously strawed, internals and barrel crown.
I've noticed the font difference on all of the 'n' suffix Alphabet commercials. I don't know why.

I still assume the barrel of this gun was replaced. Witness mark is questionable, and that's not alone. The color of the barrel and receiver is so unbalanced. The quality of the job was super, indeed, probably a "reconditioned" Luger done in the factory. I don't know how German installing barrels. It must be installed using a special tool which US gunsmith do not have -- they could install it once without leaving marks (original gun), then they could install it twice or more times without leaving marks (reconditioned gun). Looks being a factory reworked gun.

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Also, thanks for the cornellpub link. I will make a collection of those catalogs. Slowly.

Ain't nothng wrong with it.It's a 1920's commercial.