You will, at the least, recieve the following information: the gun's original date of shipment, to whom the gun was shipped (usually a retailer or distributor), and the gun's original factory configuration (barrel length, sights, stocks, etc.). The primary value of the letter, other than to satisfy one's curiosity, is to authenticate the gun's vintage and configuration. This is particularly valuable to collectors who are buying, selling, or trading rare or desirable models.
Smith, and Wesson, and Me. -H. Callahan
Well waddaya know, one buwwet weft! -E. Fudd
All bad precedents begin as justifiable measures. -J. Caesar