Lobo, they are screwed into the receiver. It is a square thread, not that it matters for disassembly, but my dad took one apart so that's how I know.
Right-hand thread, I believe... shouldn't be much different than taking a barrel off of a bolt-action receiver, once you get the extra parts (bolt, mag tube, and so on) out of the way.
Does this help or did you mean something else?