While it’s true that a self-loading pistol carries more rounds than a revolver, a pistol is more prone to malfunctions. A single action revolver requires cocking of the hammer before each round can be fired and considerable time to reload. That leaves a double action revolver.
The “service revolver” sized K-frame has several advantages over the smaller “back up gun” sized J-frame revolvers. The K-frame guns have six shots to the J-frame’s five, better triggers, a larger grip, and typically have longer barrels. While the average J-frame gun sports a 2” tube the standard barrel length on the K-frame is usually 4”. The downside, of course, is that the larger K-frame is harder to conceal than the snub-nose J-frame guns.
It’s the Smith & Wesson Model 65. This .357 Magnum revolver is a force to be reckoned with.