welcome to byc!
With those feathered legs he is definitely not an Australorp - nor does he look like a Marans - chances are, with the leakage showing, he is a mix. What color are his legs beneath the feathering? What color are the bottoms of his feet?
I would say Brahma cross , he has modified pea comb and feathered legs , also the body type is more close to Brahma than BCM ,also agree he is not black copper in color ,just has red leakage .