Very neat little handguns. I've always found them to be both fascinating and very innovative.
For instance, they improved on the Browning manufacturing design in that they lathe turned the locking lugs around the circumference of the barrel. This negated the need for milling the barrel to cut the locking lugs, and greatly speeded production.
The lock mechanism is a removable unit, making it very easy to service.
And, perhaps most innovative, the cartridge feed lips are not part of the magazine, as is normal for virtually every other handgun made, they are part of the lock unit!
By transferring the feed lips to a separate, and much sturdier, unit, magazine-related failures are virtually eliminated.
Why this particular feature has never been copied by other manufacturers is totally beyond me.