This double-action revolver is part of what Smith & Wesson calls its 3-5-7 Magnum series. These are S&W L-Frame Model 686 Plus revolvers that hold seven rounds of .357 Magnum ammo.
Smith & Wesson's 7x7 Model 686 Plus Revolver: Review - Shooting Times
Smith & Wesson's "7X7" .357 Magnum Model 686 Plus checks all the boxes.
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