It's been reported that the 342ti is THE lightest .38Spl revolver S&W has ever sold. I've actually never seen one, but I've handled the very similar 337ti, and I'm tempted to believe it! The frame actually has a groove down the backstrap to lighten it even more.
These revolvers are so light that S&W marked the barrels of some variants with .38 SPL +P JACKETED. The reason for the peculiar "jacketed" label is that +P loads with soft lead bullets (e.g. the Remington LSWCHP "FBI load") apparently have a tendency to jump crimp and lock up the gun; its recoil is that severe!