But when you log in to Samba are you using the directory's owner?
The easiest solution to this is to add
to the share's definition. That will write all files with user and group shane. In a multi-user situation, you only want to take this approach if you don't care about auditing the files people place in this directory. If you need to know that user "sue" has written a file, then you need to work harder on creating the right users and groups.
force user = shane
force group = shane
You might prefer to create a separate user and group just for the share and preserve your own username for your home directory.