Smith and Wesson devised this black powder cartridge in 1877. It was intended for the relatively weak top-break Smith revolvers of the period. Colt also chambered revolvers for the cartridge, which they called the .38 Colt New Police. As I understand it, the only difference was the flat-nose lead bullet loaded in the Colt version of the cartridge. (The S&W version used a 145 grain round-nose lead bullet.) Both claimed a muzzle velocity (MV) of 730 fps and a muzzle energy (ME) of 173 ft. lbs.

There was also a variation of the .38 S&W called the .38 Super Police or .38/200. These used a 200 grain LRN bullet at a MV of 620 fps with 176 ft. lbs. of energy.

Reloaders have found that .357" swaged lead wadcutter bullets (as sold by Speer and Hornady for .38 Special target loads) are a pretty good choice for .38 S&W reloads. These relatively soft bullets will usually expand enough to fit the grooves in .38 S&W barrels when fired. The Speer Reloading Manual No. 13 shows that their 148 grain bevel base wadcutter bullet can be driven to a MV of 701 fps by 2.5 grains of Bullseye powder, and 747 fps by 3.4 grains of Bullseye. These loads used Winchester cases and CCI 500 primers, and were tested in a 4" revolver barrel.

Note: A complete article about the .38 S&W can be found on the Handgun Cartridge Page.