Originally Posted by rwsmith

When smokeless came along and with better and stronger materials and designs some realized that the potential of the .38 case was much more than it was being used for. After blowing up a few .38 guns it was decided that the new cartridge, the .357 Magnum, was in a class by itself and is exactly the same case as the .38 except they make it about a hundredth of an inch or so longer so it can't be loaded into .38 Special guns. So they utilized that big empty space in the .38 Special.