I own a 3 digit one. Great gun. I'm sure you'll enjoy it.
There is a lot of history on them. Some bad because the military mixed parts up when cleaning, causing custom fit Reising to malfunction. You can Google it and find the story easily. Also there is a yellow book on Reising 50 that you can buy.
You might want to convert it to a inertia firing pin to prevent firing pin breakage.