Smith & Wesson Model 640

S&W 640
Type	Service Revolver
Place of origin	USA
Service history
In service	1990–present
Production history
Manufacturer	Smith & Wesson
Unit cost	$729.00
Specifications
Weight	22.58 oz. ; 15.8 oz for alloy version
Length	6.56"
Barrel length	2.125"
Caliber	.357 Magnum .38 Special .38 Special +P
Action	DAO
Effective firing range	22.86 meters
Maximum firing range	45.72 meters
Feed system	5-round cylinder
Sights	Fixed

The Smith & Wesson Model 640 revolver is a 5-shot snubnosed revolver that is chambered in either .38 Special or .357 Magnum calibers. Like other "J-frame" Smith & Wesson revolvers, it has a swing-out cylinder, but this model features a concealed hammer, and is part of the Centennial line. The Model 640 is an approved off duty/ back-up weapon for the New York City Police Department.

The first model was chambered in .38 Special and fitted with a standard barrel of 1-7/8 inch length. The second model had a slightly heavier and longer barrel of 2-1/8 inch length. The gun was constructed entirely of stainless steel. In 1995 the model 642 was introduced which was made in aluminium and designated "airweight".

A 3" barreled version was offered until 1993, when it was dropped from production. That same year S&W introduced the Model 940, similar in appearance, but chambered in 9mm Luger. In 1996 the 940 was dropped and S&W began chambering the 640 in .357 Magnum. Because of the power of the .357 magnum cartridge, the frame is strengthened just in front of the cylinder release on those models.

In 2001 a Scandium framed version was introduced in .357 Magnum designated as the Model 340. This revolver weighed 10.9 ounces.

In spite of its small frame and short barrel the revolver is durable and fairly accurate. Firearms writer Joe Gorman fired 500 full power rounds through the revolver and it survived still tight and still in time.