The Germans captured the FN factory in 1940, of course the employees weren't crazy about working for Jerry, so "Yes" quality control was lacking. Many weren't cleaned up very well before bluing and the color is well known to vary. They still functioned fine though, mine is a treat to shoot. They were issued to a large number of SS troops,, not necessarily to officers, (no supporting evidence).
Recommendations:
When shooting, get a replacement firing pin, extractor (original extractors are really frail) and use aftermarket or later production mags. I didn't see all of the magazines in your pictures but an original will have a small extension in the center of the forward edge of the bottom. Original mags are extremely hard to get ahold of and I've seen them going for as much as $400.00, that's no BS.
Problems:
I've only encountered one problem area, although known for thier poor trigger pull I have found a few of the sear pins to be soft and bend over time, (possibly employees,,, sticking it to the man LOL) causing the condition to worsen. Good replacement ones are easy to get and better quality. There is no way to know it's been replaced, some are bent bad enough that there is a risk of damaging the frame when trying to remove, if you're not careful. With good cleaning and lubrication they're not really as bad as people portray.
Here is where I get a little rusty, I don't remember the history very well, but France,,, I believe, originally commissioned John Browning to build them a service pistol. JMB had sold the 1911 patent to Colt, so he couldn't use any part (or design) in any new designs, so he had to start from scratch. Many people say that this was his correction to all the problems of the 1911,,,, "improved design" that's BS, he simply couldn't use a design that wasn't his anymore. That's why the transfer bar trigger system is used instead of the better 1911 style. Anyhow, this design was literally found on his desk after his passing in 1926. Some circles claim that he had this design done as early as 1922, but was hesitant for some reason to go to production with it, regardless of when it was done, FN still didn't produce it intil 1935.
If you send me a PM, I will refer you to someone who can give you a production date of your pistol.
Also, many are almost impossible to see, but most of the 640b's (Waffenampt Hi Powers) have a lower case letter suffix like 34863a. If you miss this letter your date will be way off, I believe they ran a, b and c, I am unaware of and d's. Also, I think yours is original finish, one of the responses has a photo of one that has definitely been polished and blued.
Hope this helps,
I have two original magazines. They are both very tight in the magazine well and I heard that it is common for it to do that. I know they are extremely rare and I don't understand how they ever could be sold separate. Mind as well just sell the gun/mags. But thanks for the info, it's a great gun for sure and you don't see too many of these.