Great to see that you are starting up a MS group, takes a bit of work to do. I am not sure however that Facebook is the ideal medium as most MS owners are not the type to use Facebook. I for one will have nothing to do with that medium but am a lover and collector of Mannlicher and Mannlicher Schoenauer rifles and accessories, paraphernalia etc. and would happily be part of a MS group.
Still, I hope it works out for you.

Matt.