Smith & Wesson N frame strain screw, blue $15.00 Part 55 on the exploded diagram. Used, excellent condition blue strain screw from a Model 57, N frame revolver. Will fit other models of N frame revolvers. Out of stock Category: Smith & Wesson Related products Smith & Wesson K frame Extractor rod spring $5.00 Smith & Wesson K frame center pin spring $5.00