Judging by the serial number and the pics, I'd say the 1930s date is more likely. My regular horn is a Conn 6M that's numbered, I think, in the 260,xxx range. Here's a good articles about the history of the instrument:

http://www.stohrermusic.com/2012/10/conn-transitional-6m-saxophones-the-finer-points/

It's a bit difficult to see, but I think the horn has rolled tone holes, which, according to this article: http://www.saxpics.com/conn/artist.htm, Conn stopped using beginning in 1948.