I am looking for some of the wrot copper barbed sweep elbows that were
formerly used for 1/2" Qest polybutylene piping.

I don't see Copper barbs but many others for PB pipe..Check out Catalog page
192 in particular or Call/Email Naughtons. They've never NOT had whatever
I'm looking for.
http://www.naughtons.com/NAUGHTONS/PDFS/14PIPE.PDF