OK good test but I would think if you just submerge your rifle in the bathtub with a loaded cartridge and the barrel taped you should be able to find out for sure by drying the outside off removing the tape and inspecting the bore!! Someone needs to try this!!! But you must have a cartridge in the chamber..
Me, I would use a dummy loaded cartridge as the hole in the bathtub and subsequent police investigation would make the newspapers...
