Prototype update
I made a harmonica derringer prototype out of paper, here’s some pictures:
https://imgur.com/1P1vBJs
https://imgur.com/dBNrudR
https://imgur.com/mgsvSGu
https://imgur.com/Fwd8W1U
https://imgur.com/AKrVuz5
The harmonica (magazine) holds 11 rounds, and i made it heavy, 7mm walls between each chamber. Since i aiming for a .22lr it could be made lighter and smaller, or in the same length containing more rounds.
I think i will use mild steel sheet to make this gun, except for the hammer and trigger that need to be hard. The chamber and the barrel will be made of tempered 4340 steel, i think, i read that it is stronger than 4140 and can be brought pre-hard, so it doesn’t require any heat treatment after working with it. But feel free to give me your thoughts about steel choice of this gun.
I will use a ball bearing detent, or two, to index the harmonica.
However, the advantages of this harmonica derringer against a revolver, is that it holds more rounds. You could easily carry two magazines, which will give you 22 rounds, in this case. The risk of a accidental discharge is very low, or basically non existent, if you don’t carry the magazine inserted into the gun.
The disadvantage is that it’s bulky when the magazine is inserted into the gun, and you have to manually operate the magazine, i didn’t find any good solution other than that, and i don’t think it will be that much of an issue, it will still be easy and fast operated.
If the harmonica is positioned below the barrel instead of along, it could be made less bulky when inserted, the bad side of this, is that the magazine will travel up and block the sight, and in this derringer case there is no space for a design like that, since your trigger finger is located below.
I think i will make a version with the magazine below, but i think i will use a open bolt action instead of a hammer.
Eventually i will experiment with my other designs to, but i think many of them will fail and be unsafe to shoot.
Anyway, give me your thoughts about this project.