"getting my creative work back,and into the public domain."

Capt. - I'm not sure you meant it that way, but "public domain" in the legal sense means that everyone owns the rights and can release recordings without compensation. In television and film, many older productions have gone beyone the copyright period and the rights were never, or could not, be renewed. This enables anyone to release copies of it. If you look at some of the old Laurel and Hardy films, you will find multiple companies releasing copies of the same feature - each with different quality depending on their source.

Has anyone explored the possibility that some of the copyright laws might have expired and the rights for these recordings could be up for grabs?

I also know that many artists have re-recorded their original recordings just for the reasons you mentioned.   Obviously that can't be done for some of the recordings in question, but is that an option in your case?