Guy, I can’t answer your question completely. There would be so many factors involved there, I would think. How tight the empty case at the muzzle end was in there (probably more a product of the quality of machining or the dimensions of the chamber, than of the ammo), the velocity and perhaps shape of the projectile attempting to push it out, etc.
I can tell you that a South African version of the home-made Filipino “Bang Gun” worked the same way. One loaded a round in it and fired it. then turned the barrel around and loaded another round and fired it, expelling the first round’s empty case as well as the projectile from the second round.
While hosting one of my dear friends who was a Criminalist with the South African Police at one of their National Crime Labs, here for an AFTE (Association of Firearms and Tool Examiners) meeting and some touring, he showed me some X-rays taken of a youngster’s head, clearly showing both a revolver bullet and a .38 revover casing in the young man’s brain. He was killed in an accidental shooting with one of these guns being played around with by young kids. The doctors were amazed and contacted the police, and Paul could immediately identify the type of weapon used in the shooting.
For those that might not know, these crude firearms are basically a pipe with a pipe. The action is a pipe with a nail at the real end acting as a firing pin. The second pipe is smaller diameter, picked to fit whatever ammunition the maker of the device could obtain, or had, and fits inside of the first pipe. A round isloaded in the rear of the smaller pipe and it is then inserted into the larger one. When it is desired to fire this contraption, the smaller pipe is pulled hard towards the rear, much like working a pump shotgun, and the round is fired by the fixed firing pin.
During WWII, in the Philippines, this was a gun to get a gun. They would hold together for a few rounds, and were used to dispatch an enemy soldier so that the soldier could be stripped of his weapon and ammunition. They were used by Guerrillas fighting the Japanese. I don’t know that they ever used them in the manner described for the derringer and the “zip guns” made in South Africa, though. It is amazing that these things don’t blow up, but I guess the pipes are thick enough to contain the pressure for a few shots, and that’s all they are really intended to fire. But then, maybe they do blow up from time to time! I wouldn’t make one or shoot one on a million dollar bet!
I suspect the original derringers worked o.k., but I would think that the whole system would have been looked upon as pretty silly, with much better systems available, by the time the metallic cartridge came into any real use. Probably why they made so few of them few people have ever even heard of them.
What caliber or cartridge type was used in the gun you mentioned in the original question, do you know? It would be interesting to know. I am one of those that had not heard of this particular handgun before.