Press in the recoil spring plug from the muzzle of the gun (it's the knurled thing located under the outer barrel.)
Rotate the barrel bushing till it stops.
Extract the barrel bushing and recoil spring plug
Push the outer barrel out from the inside.
Disassemble of all these main parts is exactly like real steel - there's several guides on this online with pictures. Search "1911 barrel bushing"
Here's one:
http://www.bobtuley.com/45/pistol_03.htm