Saxon and Shear-stress,
The serial number reflects a manufactuiring date, not a shipping date. The original poster asked for a date of manufacture.
S262000-S289999: 1966-1967
S290000-S304999: 1967-1968
S305000-S329999: 1968-1969
When a numerical sequence is set up like this, I usually assume the number group S290000-S304999 would begin at the start of 1967 and end when 1968 began, especially when 1968-1969 is assigned an entirely different number group.
If 1968 starts of with S305000, then it is reasonable to deduce that S2977xx came previous to 1968. If 1967 started off with S290000, a conclusion that S2977xx came after the beginning of 1967 can be made.
Of course this could be a revolver that had the butt stamped during the Christmas holidays, and was finally finished and shipped after New Years. However, there were approximately 7200 revolvers of a 14999 item production run made after the revolver in question. In other words, about half the entire production run occured after Mr. Dewey's revolver. That amount could have been cranked out at the end of December, I suppose, but I think the likelihood is slim. Chances are, a serial number that occurs near the median of the numerical group probably can be assigned to the year in question.
Draw your own conclusions from the numbers. If you want a definitive answer on a shipping date, contact
Roy Jinks.