Like everyone's said. Wire underfolder, stamped reciever, plastic handguard, and a 5 round magazine. That's about as light an assault rifle I think exists.
But, don't forget. The underfolders are usually frowned on because they're not stable. They flex and move to easy.
I'd suggest you carry a .44 mag. pistol if weight is that big an issue and you want large animal stopping / hunting ability.