The method originally used to measure the velocity from the Luger involved the bullet severing two metal foil strips placed about 15 m or 50 ft apart. The foil carried a current. When the first strip was severed it interrupted the current to an electromagnet releasing a weight. The second strip on being severed induced a spark that marked a tape pulled by the falling weight. The method was actually quite accurate. One should bear in mind that what was actually measured was the average speed from around 5 feet to 55 feet. (The same method was used in both metric and English unit countries, 50 ft between strips in English countries pistols, 100 feet for rifles.) It's more accurate than the ballistic pendulum.
I did the ballistic pendulum thing for my project in my first college physics class. I suppose that's giving away my age. Fancy dragging a big bore revolver into the physics building these days!
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