I commonly see Paul's letters dated to around this time, but I haven't seen any reasons listed for why this is except that it says so in Acts, but Acts is usually agreed not to be historical.
EDIT: I didn't get an answer, so I started a new thread over in /r/AcademicBiblical https://www.reddit.com/r/AcademicBiblical/comments/4293hg/why_are_pauls_letters_dated_to_around_50_ce_xpost/
If you don't get an answer here try the AcademicBiblical subreddit.
Saying Acts is or is not historical is like saying books are either "literal" or "not literal." Acts certainly has some historical information in it.
We know that Paul met James the brother of Jesus in Jerusalem (Gal 1:19). From Josephus (Ant. 20.9), we know that James the brother of Jesus was executed right around the death of Festus, which was 62 CE. We know that Paul was an adult well before he became a follower of Jesus, and we know that Paul did some traveling before he came to Jerusalem to meet James (again all Gal 1). All this and the fact that Jesus died around 30 and that Paul probably doesn't mention the destruction of the Temple makes it pretty certain he wrote at the very earliest in the 40s and the latest in the 60s.