In the aftermath of the 1986 FBI Miami shootout, the FBI started the process of upgrading their service arms to a weapon of much greater power than their collection of 9x19mm Parabellum automatics and .38 Special revolvers. This search led them to the 10 mm Auto that had been developed in the early 1980s for the famed Bren Ten, but by this point in time the company had already gone out of business. The FBI then contracted Smith & Wesson to develop a new automatic for the 10 mm Auto, creating the Smith & Wesson 1076.
After testing the new weapon, the FBI found that the recoil was too powerful to control easily, and the large rounds made the gun difficult to hold for smaller men and women. The FBI asked for several changes to the 10 mm Auto, using a reduced-charge version often referred to as the "FBI load" or "10mm lite." The case capacity of the 10 mm Auto was more than required for this "10 mm lite" load, so Smith & Wesson then redesigned the cartridge to make it shorter while maintaining the performance of the FBI loading. They also decided to use a small pistol primer, rather than the large primer used for the 10 mm Auto. With the .40 S&W being shorter than the 10 mm Auto and approximately the same overall length as the 9x19mm Parabellum cartridge, many existing 9 mm pistols could be easily adapted by their respective manufacturers to fire the new cartridge.
The .40 S&W cartridge debuted January 17, 1990 along with the new Smith & Wesson Model 4006 pistol, although it was several months before the pistols were available for purchase. Austrian manufacturer Glock beat Smith & Wesson to the dealer shelves in 1990, with pistols chambered in .40 S&W (the Glock 22 and 23) which were announced a week after the 4006. Glock's rapid introduction was aided by its engineering of a pistol chambered in 10 mm Auto, the Glock 20, only a short time earlier. Since the .40 S&W uses the same bore diameter and case head as the 10 mm Auto, it was merely a matter of adapting the 10 mm design to the shorter 9x19mm frames. The new guns and ammo were an immediate success.
The 40 S&W case length and overall cartridge length are shortened, but other dimensions remain identical to the 10mm Auto. Both cartridges headspace on the mouth of the case. Thus in a semi-auto they are not interchangeable. Smith and Wesson does make a double action revolver that can fire either at will using moon clips. A single-action revolver in the 38-40 chambering can also be modified to fire the .40 or the 10 mm if it has an extra cylinder. The .40 will at short range take deer; it is also suitable for small and medium game. The reduced power of the round compared with the 10 mm Auto it was based on led to derogatory names such as ".40 Short and Wimpy" or ".40 Slow and Weak.
IMI attempted a similar cartridge in the 1980s, called the .41 Action Express (or .41 AE) for the Jericho 941 pistol. This cartridge was based on the .41 Magnum case, cut down to fit in a 9 mm frame, and using a rebated rim the same diameter as the 9 mm Luger. The .41 AE is ballistically similar to the .40 S&W, to the point that some reloading manuals suggest using .40 S&W load data in the .41 AE. The .41 AE is a more attractive cartridge in many ways, as the rebated rim allows a simple barrel and magazine change to allow most 9 mm guns to be converted to .41 AE. The .41 AE uses 0.410-inch (10.4 mm) bullets, whereas the .40 S&W uses 0.400-inch (10.2 mm) bullets. However, as it lacks the backing of ammunition manufacturers in making .410 caliber bullets suited to semi-automatic pistols, the .41 AE has not achieved widespread popularity.