Rights in public folder

Hi,

I have a Ubuntu Server which acts as a file server. I've installed Samba, as there are some Windows PCs in the network.
I've created a public folder. Everyone has rw-rights in this folder. So far, so good. But everytime a user (which is logged in) saves a file in the public folder, that user is the only one with rights on that file.
Is it possible that files saved in that public folder always get 777 permissions (the server is not connected to the internet, so there are no security issues whatsoever).

Regards,

Fabian

I guess it should be some samba configuration parameter to tweak