create mask vs force create mode

In in newly samba setup i want full permission for every user, so i specified parameter
create mask = 777
But result was not as per expectation , what permission i get on newly created files inside share folder was 766, it surprised me. Hint i got from samba list is that ' create mask' work along with umask parameter. if anyone want to overcome umask value 'force create mode' is right option.
Now my problem get solved by setting
force create mode =777