Many reference works do indicate the scalloping in the follower is a trait of the 9mm red nine. I have been to a few recent auctions with some vintage prussian contract red nines and the scallop was present. Here is one on line source, although I cannot vouch for his credentials he does seem to be knowledgeable about the broomhandles. Just wondering if maybe this is truly a red nine feature.
http://askmisterscience.com/1896mauserbackup/index.html