The Smith and Wesson 340PD is an ultra-light, J-frame, five shot, short-barrel

Gun barrel

A gun barrel is the tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity....

 revolver

Revolver

A revolver is a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing. The first revolver ever made was built by Elisha Collier in 1818. The percussion cap revolver was invented by Samuel Colt in 1836. This weapon became known as the Colt Paterson...

 chambered for .357 Magnum ammunition.

Design

It has a frame constructed of scandium

Scandium

Scandium is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic transition metal, it has historically been sometimes classified as a rare earth element, together with yttrium and the lanthanoids...

 enhanced aluminum alloy, a titanium alloy

Titanium alloy

Titanium alloys are metallic materials which contain a mixture of titanium and other chemical elements. Such alloys have very high tensile strength and toughness , light weight, extraordinary corrosion resistance, and ability to withstand extreme temperatures...

 cylinder

Cylinder (firearms)

In firearms terminology, the Cylinder refers to the cylindrical, rotating part of a revolver containing multiple cartridge chambers. The cylinder revolves around a central axis in the revolver to bring each individual chamber into alignment with the barrel for firing...

, and a corrosion

Corrosion

Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...

 resistant steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 barrel liner. Unloaded it weighs only 12 ounces (340.2 g) and when loaded remains under 1 pound (0.45359237 kg).

With no external hammer

Hammer (firearm)

thumb|150px|Hammer with an integral [[firing pin]] on a [[S&W Model 13]] revolver The hammer of a firearm was given its name for both resemblance and functional similarity to the common tool...

 it operates double action only and is a popular choice for concealed carry.

Design limitations

There is a prohibition against using ammunition with bullet weight less than 120 gr due to the risk of frame erosion

Flame cutting (firearms)

Flame cutting is a destructive phenomenon that occurs in some firearms as a result of hot gases under high pressure.The most common manifestation is on the underside of a revolver top strap, where the hot, high-velocity gases released when a round is fired begin to cut through just above and in...

 from powder that is still burning after too rapid exit of the light projectile. Another warning in the owners manual is that recoil

Recoil

Recoil is the backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile and exhaust gasses, according to Newton's third law...

may pull the cases of unfired rounds in the cylinder rearward with enough force to unseat the bullets causing the cylinder to jam. It has also been said that accuracy is compromised in these types of ultra-light revolvers since the barrel is a steel sleeve liner rather than a single solid piece of steel.