Another FYI
Recessed chambers make sense on a rimfire revolvers because they support the thin rim area of the case that contains the priming compound but also must contain the pressure generated when the round is fired. They were a "frill" that was incorporated into Magnum revolvers but, since they really served no function (the rim area on a centerfire cartridge is solid and is usually adjacent to a substantial web area), the recessed chambers were deleted in the interest of reducing manufacturing costs.
It's not uncommon when perusing ads for the older S&W revolvers to see "P&R, TT, TH, RR, WO." The latter terms are "target trigger" (wide and grooved), "target hammer" (wider spur for easier thumb-cocking), "red ramp" (red insert in the front sight) and "white oulline" (a white line outlining the square notch in the leaf of the rear sight).