Just a couple of thoughts on the above response.
Prior to 1980, revolvers dominated the LE market and Smith & Wesson dominated the LE revolver market. The K-Frame was by far the most popular. Bill Jordan's original concept for the Combat Magnum was to have a handy, light revolver with target stocks and adjustable sights for LEO's who would fire .38 Special ammo for practice but only shoot .357 magnum ammo for qualification and duty. Previous to the introduction of the Combat Magnum, S&W's .357 magnum revolvers were built on the N-Frame. Enter the dawn of the light weight, high velocity bullet ammunition in the 1970's. SuperVel was the earliest and leading manufacturer of this ammo and this same type of ammo became extremely popular in the LE & commercial communities. The Combat Magnum which was engineered to be used with a limited amount of the then standard 158 grain magnum ammo and not being bombarded with a steady diet of hyper-velocity (at the time) 110 and 125 grain ammo. It wasn't designed for it and barrel failures were relatively common. To assume that Smith & Wesson developed and initiated the manufacture of an entirely new frame size based on relatively rare and isolated failures is pretty unrealistic IMV. So is the notion that the switch from the pinned barrel to the "Crush Fit" process played a part in the failures. IMR, the L-Frames were the first S&W's to feature the Crush Fit barrels. No pinned barrel L-Frames were built to my knowledge. "Crush Fit" is a manifestation of S&W's marketing propagated by the firearms press. This is because the mechanics of fitting the barrel to the frame are essentially identical whether the barrel is pinned or not. The major difference is the pin and the slot in the barrel shank. Pinned barrels are not just screwed into a frame until hand tight and then a retaining pin installed.
Anyway, used K-Frame .357's should be closely inspected for this issue before purchase. Smith & Wesson no longer has replacement barrels in any length for the old K-Frame .357's and suitable used barrels are hard to come by.
Bruce