First introduced by Smith&Wesson in 1990. Ballisticly similar to the 9mm parabellum, but with muzzle velocity exceeding all 9mm loads, and exceeding most standard loads of the outdated .45ACP cartridge, while having a standard magazine capacity of as many as 15 rounds (G22) as compared to the 7 round standard 1911 magazines, or the awkward-to-hold 13rd G20. Despite the belief or most inexperienced with the round, the .40 S&W has noticeably more recoil then the .45ACP.
Ironically, Austrian manufacturer Glock beat Smith & Wesson to the dealer shelves in 1990, with pistols chambered in .40 cal.
A .40 cal is not a big fucking gun, it's an improved version of the 9mm. What it really is is a 10mm bullet, and packs more punch than the 9mm, but still allows for the same (high capacity) amount of rounds to be held in a clip. A favorite of drug dealers.
"Still tote a glock .40 for the haters and the bustas" -T.I "A.S.A.P"