As far as authenticity is concerned, much of what is referred to as
bronze in period pieces (Dark and Middle Age Europe) is now being
referred to more and more as "copper alloy" in texts. I know much
of what used to be called bronze objects in the Viking period, for
example, are alloys that would now be called brass.(often with some
lead thrown in that is believed to help it cast better.)
I know this doesn't really answer your question, but I was just
reading a discussion on this topic and thought I'd throw it in.