Smith & Wesson K frame hammer block, blue $20.00 Part 78 on the exploded diagram. Used, excellent condition hammer block from a 19-4, K frame revolver. Will fit other models of K frame revolvers. Only 1 left in stock Smith & Wesson K frame hammer block, blue quantity Add to cart Category: Smith & Wesson Related products Smith & Wesson K frame mainspring $15.00 S&W 39/439/3904 series XP magazine springs 3 pak $34.97