With the approaching of swing-out cylinder revolvers equally S&W and Colt would chamber the .38 S&W, even so Colt labeled “their” cartridge the .38 Colt New Police. The .357 Magnum is basically similar to a .38 Special, but the case is more time to permit far more space for propellant, https://trevorfztac.blogoscience.com/32097356/not-known-factual-statements-about-38-special-bullets-for-sale