Smith & Wesson N frame mainspring $15.00 Part 88 on the exploded diagram. Used, excellent condition mainspring from a Model 57, N frame revolver. Will fit other models of N frame revolvers. In stock Smith & Wesson N frame mainspring quantity Add to cart Category: Smith & Wesson Related products S&W 59/459/5904 series XP magazine springs 3 pak $34.97 Smith & Wesson M&P 9mm .40/.357 Recoil Spring 16lb. $14.97