Ubuntu – Change user’s primary group – have new files made in that group

I am setting up an environment where I am giving several users SSH access on my server. They are all trusted, but I want to corral them into a segment of the filesystem. I created the users like so:

adduser username -ingroup groupname

which works well enough. When I log in as one of them I can do this and get all the right answers:

$id -r -u -n
username
$id -r -g -n
groupname

I switched my own user account's primary group to groupname by doing this:

$usermod myuser groupname

I then logged out and back in. Now the files I would like the group to be able to access are under here:

$ls -l / | grep groupname
drwxr-xr-x  3 root     groupname    4.0K 2012-03-26 20:20 groupfiles
$cd /groupfiles
$ls -l 
drwxrwxr-x  2 root groupname    4.0K 2012-03-26 20:32 project

The permissions are by design, members of the group cannot alter files/folders under /groupfiles but they can add, edit, and delete under /groupfiles/project

The problem I'm having is that when I do this, I get the wrong group:

$touch test
$ls -l test
-rw-rw-r-- 1 myuser myuser 0 2012-03-26 20:58 test
$id -r -g -n
groupname

I need to make it so that the files created by vim, touch, etc have the correct group. I'm aware of newgrp() and the setgid bits. These are not what I am looking for. This works fine for the new users's I created, but doesn't work for my user. I'm not sure what happened, but it is working fine now. I've just leave this question here for future tinkerers.