The Smith & Wesson Model 640 revolver is a 5-shot snubnosed revolver that is chambered in either .38 Special or .357 Magnum caliber introduced in 1989.
== History == 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. A 3" barreled version was offered until 1993, when it was dropped from production. In 1995 the model 642 was introduced which was made in aluminium and designated "airweight". In 1996, 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.
== Design == The gun was constructed entirely of stainless steel. 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.
Variants
=== Model 940 === Produced from 1993 to 1996 Similar in appearance to 640, but chambered in 9mm Luger
=== Model 340 === Scandium framed Introduced in 2001 Weighed 10.9 ounces Chambered in 357 Magnum
== Users == United States New York City Police Department Carried by officer Walter Weaver during the September 11, 2001 attacks Currently displayed in the NRA National Firearms Museum in Fairfax, Virginia