Sometime ago, around 1940, an American writer stated that the gun used was a .32 caliber Browning 1900. Since very few Americans were able to contradict that, the story took root and has been repeated numerous times by other writers, none of whom had any basis other than the original incorrect story.
Some 20 years ago, an article by Prof. Jiri T. Vojta, in AutoMag, gave the complete story, including the serial numbers of the four .380 caliber Model 1910's involved. Prinzip's pistol was 19074. It and the others had been in a Vienna museum, but disappeared during WWII. Several years ago, Prinzip's pistol was found and restored to the museum; the others, AFAIK, have not been found.
Jim