[jmichna]

Handgun sale between parties from two different states must go through an FFL; it's a Federal requirement. You must receive a handgun in your home state. If you purchase it in another state (MO), it must be shipped to an FFL in the state where you are living (IL) to do the paperwork. Also, as an IL state resident, you need to hold a current, valid IL FOID.

Here's an earlier thread that happens to cover your question:
http://www.xdtalk.com/forums/sa-xd-...ll-gun-ftf-when-ffl-involved.html#post2864885