617 Light Barrel
I was able to buy the non-underlug versions (4" and 6") in the 1980s. I think they were in a short run production, while the full underlugs were being sold. They were in stainless steel, 6-shot.
Later, S&W started making weird variations of the full-lug guns, including 10-shot cylinders, alloy, etc. As usual, the marketing people seemed to have very little knowledge about gun common sense and experience! I think they were fresh out of MBA school, and concentrated on the cosmetics, rather than practical issues. I met some of them, rather young people, and I was surprised at the lack of knowledge they had about guns.
In recent years, I don't think they did any customer surveys to determine the wishes of the customers. Light calibers, like .22 LR, had heavy lug barrels, and heavy calibers like .357 or .44 were sold in small lightweight short-barrel guns, which would damage the nerve endings in your hand! These little monsters were marketed to women. Many women (and men) would develop a severe flinch from the recoil, and be hesitant to fire them after the first shooting experience. So much for the actual effectiveness in a self-defense situation. My wife's purse already weighs a ton, so a hefty gun wouldn't even be noticeable inside it.