Remember even according to the new EU regulations anything recorded and first released prior to late 1961 remains in the P.D. in Europe and even by U.S. standards anything recorded prior to early 1943 (currently) is P.D. in the U.S. (70 years!). And even a 1943 cutoff date covers quite a lot of those "Chronogical" platters.
In short, most of the swing era definitely has gone P.D. by now.
I thought the US copyright was now for 90 years but before I posted this I Googled US Copyright Laws for recordings but this website:
http://www.pdinfo.com/Copyright-Law/Public-Domain-Sound-Recordings.php
claims that no US recordings will become PD before 2067!