50-500 uSD
In order to determine when it was shipped from the factory, the serial number must be provided. You could call Smith and Wesson and provide the serial number and they will tell you for free. You can request a letter from them for @ $50 USD that would also answer your question. The Blue Book of Gun Values has sn data in it and most book stores or libraries will have one.
Open your revolvers cylinder. Look at the forward hing of the cylinder under the barrel. The numbers you see under the barrel at the hing is your model number. Examples would be 642, 638, 442 ect. Sometimes there is a dash such as 642-3 or 638-3 but the first 3 numbers are the ones that matter the most. Could be the Chief's Special Airweight (standard 5-shot .38 Special with exposed hammer)or Bodyguard Airweight (same gun with humpback hammer shroud).
79.75
What does 638 mean
638
507-638 = -131
638 + 577 = 1215
253 + 638 = 891
638 x 2.9 = 1850.2
638 x 34 = 21,692
Less than 15 cents.
The factors of 638 are 1, 2, 11, 22, 29, 58, 319, and 638. The prime factorization of 638 is 2 x 11 x 29.