Feb 16, 2019
RAY: During World War II, American infantrymen carried a rifle that used .30 caliber ammunition. Now, you may ask, what is a .30 caliber bullet? I don't really know what the arcane measurement is, but it happens that 7.62 millimeters is .30 caliber bullet, or 308/1,000 of an inch.
When hostilities broke out between us and the Japanese, they hurriedly began to make rifles that would fire a .31 caliber bullet, or a 7.7 millimeter bullet. Why would they do this?
RAY: Well, one part of it, I think, is pretty obvious. And that is, if they had to vacate a position and their ammunition were captured, it would be unusable to the Americans. But the other part of it isn't so obvious. If the reverse happened -- that is, if the Japanese captured our ammunition -- the smaller-caliber bullet would fit in their rifles, and they would be able to use our bullets to fire on us.