S&W Model 36 Date of Manufacture. By roguesam in forum New Members Introduction Replies: 17. Smith and wesson model 41 serial number dates. F) serial number, and if there is a letter in front of or anywhere near the s/n on the bottom of the grip g) Model number if it is under the crane. That number, if it is the s/n, should come from the butt of the grip (or under the barrel or face of the cylinder). The BBL would be 5.5' They also made some with 7' and some early examples with a 7 3/8'. I can't help you much with the date. The semiautomatics started with serial number 1001 in 1954 and continued up to serial number 115001 in 1970. When, as you mentioned, the A prefix began.