Smith & Wesson K frame mainspring $15.00 Part 88 on the exploded diagram. Used, excellent condition mainspring from a 19-4, K frame revolver. Will fit other models of K frame revolvers. Out of stock Category: Smith & Wesson Related products S&W 6904/4006 series XP magazine springs 3 pak $34.97 Smith & Wesson K frame center pin $20.00