If you install a barrel in a CNC lathe and shoot a cartridge in it, will it make your lathe a firearm? Well, theoretically – yes (arguable), practically – not really, from the standpoint of law – probably depends on circumstances and how any particular legislation defines firearms. Anyway, folks at Serbu Firearms did exactly that. They secured a 3.2″ long .22LR barrel in the chuck of a CNC machine and ran the tailstock (with some sort of tool installed in it) at a sufficient speed to hit the .22LR case rim and ignite the priming compound. Serbu calls this “World’s largest .22LR pistol”.
Now, this is really fun and I am sure you guys enjoyed the video as much as I did. However, besides being cool, it also reveals something very interesting.
If somebody told me about it before I saw the video, I would bet that the unsupported portion of the .22LR case head would rupture and blow half of the gases rearward. The .22LR case has a very thin case head web thickness, nothing like any centerfire cartridge. So without being fully supported by the bolt, it should not withstand the amount of pressure generated during firing. As it often happens, something obvious in theory doesn’t prove to be so in practice. As you can see from the video, the .22LR case did not fail. Although seems like it significantly bulged at the unsupported portion of the case head.