Welcome to the Forum. As Pine_Worker says, according to the "Standard Catalog of Smith & Wesson 4th Ed." your Model 27-2 N692864 is probably very late 1979 or very early 1980 (s/n N700000 began in 1980). Smith & Wesson produced N-frame revolvers in 1980 with s/n's ranging from the late N600000s into the early N800000s, so there is a little guess work involved. Perhaps some other more learned Forum members have revolvers with s/n's close to yours and can better provide you with a date. Do you have any other details about your .357 Magnum that you can share with us...barrel length, box, presentation case, anything else of interest? Any pictures you can post!