Apache usually runs as a different user, so it falls under "Others". If you chmod 770, it can't access the files and so can't display them.
If you control your environment (host yourself) then you can chown to the user:group (debian is www-data) and set chmod 770, because www-data is already the owner and group. This might not work if you are pushing out of your /home/public_html directory (I usually use /var/www/$sitename)
Hi to the board, by the way.