It was something my Dad, a WW2 veteran, heard about the Japanese and he used to tell as one of his sea stories. It was proof to the WW2 generation that the Japanese had been planning their dastardly deed (Pearl Harbor) for a long time. Supposedly the Japanese had chambered their rifle to shoot their ammunition and American ammunition, but since the Japanese round was 31 caliber, we could not shoot Japanese ammunition in our rifles.
What was not discussed was why the inscrutable Japanese would also make the receivers of their Arisaka’s so short that a 30-06 would not fit in the magazine.
In so far as the Civil War, a book I have read by CSA General Porter says the Confederates were armed with everything, from flintlocks, with the majority being armed with smooth bore muskets till about 1863, when they had captured enough Yankee cap locks that they could standardize ammunition. Till then, General Porter had a heck of a time supplying ammunition to units which had every different type of sidearm conceivable.
The Confederates recycled anything that could be recycled. As an example, the rusty M1840 and scabbard was found in a barn in Monticello Arkansas in 1951. The last military action of the Civil War in Arkansas was a skirmish at Monticello on May 24, 1865. I believe the sword and scabbard to be an example of Confederate recycling. The scabbard construction is not the same as the original Ames shown in the photograph, lead solder, brass rings, and I believe the scabbard is Confederate even if the sword is not.