I like the idea of being able to ballpark dates, but there is another issue that hasn't been discussed. Firearms go from the factory to distributers and then to shops. There's no saying how long they sit at the distributer's warehouse, or how long they sit on the shelf before purchase. As an example, if I posted the SN of a Remington 700 I bought new, you might think that had some correlation to the year of manufacture, yet I had looked at that rifle sitting in the rack for years before I bought it (IIRC it had two-three inventory stickers on the back of the tag).
So I think the bottom line is that to get ballpark dates that are fairly accurate we would need a fairly large sample.
So I think the bottom line is that to get ballpark dates that are fairly accurate we would need a fairly large sample.