The Smith & Wesson M&P 340 is a 5-shot double-action-only revolver chambered in .357 Magnum / .38 S&W Spl +P. The Scandium alloy frame brings it down to 13.80 oz. (0.9 lbs.), which is light enough for pocket carry. At 6.3" overall with a 1.88" barrel, it disappears in a front pocket holster or IWB carry without much profile. 
 

Key Specifications 

• Brand: Smith & Wesson 
• Model: M&P 340 
• Caliber: .357 Magnum / .38 S&W Spl +P 
• Action Type: Double Action Only (DAO) 
• Capacity: 5 Rounds 
• Barrel Length: 1.88 inches 
• Overall Length: 6.3 inches 
• Weight: 13.80 oz (0.9 lbs) 
• Finish: Matte Black Scandium Alloy 
• Sights: XS Sights 24/7 Night Front, Integral U-notch Rear 
• Grip Material: Black Finger Grooved Polymer 
   
  The DAO trigger and concealed hammer profile mean nothing to snag on a draw from concealment. XS Sights tritium front dot is visible in low light without adding height above the cylinder. The Scandium frame is strong enough for +P .38 Spl and full-power .357 Mag, though most shooters use .38 Spl +P for regular practice given the recoil difference. The finger-grooved polymer grip is minimal for concealability but gives enough to hold.

The M&P 340 gets a mix of strong endorsement and honest caution depending on the shooter's priorities. Its best trait is size-to-caliber ratio: 13.80 oz. with access to .357 Mag is hard to match for deep concealment. Reliability and simplicity from the DAO revolver design are cited as real advantages, particularly as a backup or pocket gun.

The main practical concern is .357 Mag recoil in a sub-14 oz. frame - it's sharp, and most owners acknowledge that regular practice with full-power loads is uncomfortable. Most end up training with .38 Spl +P and carrying .357 Mag for actual use. The 5-round capacity is accepted as the trade-off for the size, though it comes up in comparisons to higher-capacity compact semi-autos.

The DAO trigger pull weight is occasionally described as heavy for precision work under pressure. Pricing relative to comparable lightweight revolvers generates some debate, but owners generally accept it given the Scandium construction. Overall feedback is positive for its intended role.