Aussie Anti-aircraft, not infantry. Both they and Roy Brown claim the kill. And it wasn't "a few dozen rounds" IIRC, they found a rather large single hole in his chest. As a testament to the gentleness of most WW1 aircraft designs, he didn't so much crash as glide and make a "deadman" landing before nosing over behind the Allied lines.
Of course his plain was completely dismantled for souveniers within a matter of minutes afterwards. I remember reading a biography about him years ago. Pretty cool guy, but his brother, Lothar, doesn't get nearly the credit he should.