.40 S&W
.40 S&W FMJ flat-point cartridge
Type	Pistol
Place of origin	United States
Production history
Designer	Bob Klunk
Designed	January 17, 1990
Produced	1990–present
Specifications
Parent case	10mm Auto
Case type	Rimless, straight
Bullet diameter	.400 in (10.2 mm)
Neck diameter	.423 in (10.7 mm)
Base diameter	.424 in (10.8 mm)
Rim diameter	.424 in (10.8 mm)
Rim thickness	.055 in (1.4 mm)
Case length	.850 in (21.6 mm)
Overall length	1.135 in (28.8 mm)
Case capacity	19.3 gr H2O (1.25 cm3)
Rifling twist	1 in 16 in. (406 mm)
Primer type	Small pistol
Maximum pressure	35,000 psi (240 MPa)
Ballistic performance
Bullet mass/type Velocity Energy 10.69 g (165 gr) Federal FMJ 1,130 ft/s (340 m/s) 468 ft⋅lbf (635 J) 7.45 g (115 gr) Cor-Bon Glaser 1,400 ft/s (430 m/s) 500 ft⋅lbf (680 J) 10.04 g (155 gr) Federal HST 1,160 ft/s (350 m/s) 463 ft⋅lbf (628 J) 8.74 g (135 gr) Underwood JHP 1,400 ft/s (430 m/s) 588 ft⋅lbf (797 J) 12.95 g (200 gr) Doubletap FMJ FP 1,050 ft/s (320 m/s) 490 ft⋅lbf (660 J)
Test barrel length: 4 inches (100 mm) Source(s):

The .40 S&W is a rimless pistol cartridge developed jointly by major American firearms manufacturers Smith & Wesson and Winchester. The .40 S&W was developed from the ground up as a law enforcement cartridge designed to duplicate the performance of the Federal Bureau of Investigation‘s (FBI) reduced-velocity 10mm Auto cartridge which could be retrofitted into medium-frame (9mm size) semi-automatic handguns. It uses 0.40-inch (10 mm) diameter bullets ranging in weight from 105 to 200 grains