The Luger, an early semi-automatic pistol, was an adaption of the 1893 Borchardt pistol. George Luger took an unwieldy pistol and turned it into a 20th Century icon. An overly complex machine, the fact that it worked at all was miraculous. As all other semi and full auto designs worked from spring loaded slides, this pistol had a toggle joint that stayed locked till the pressure from the cartridge dropped, then cammed the toggle joint up and dispensed with the old round, and on the way back introduced a new round to the chamber and was ready for firing in less than a second.
DWM Luger image from Adams Guns
The pistol was very complex, and it took many intricate machining steps to make the parts. Anyone who disassembled one of these firearms would attest to the fact that these Germans who built it were born with machine tools. It was to the German war effort's relief in WW2 that Walther developed the P-38, as they now had a pistol that could be made in a reasonable amount of time. They could make 5 Walthers with the same resources that it took to make one Luger.
Still in all, the Luger is an amazing machine. And a hundred years later they are still working, a fact of life for 19th Century designs. This animation from siamkatze's channel shows the inner workings...