For a survival rifle I'd want something other than a semi-auto ... a lever action or bolt action. They are far less sensitive to dirtiness and different ammo. Since you, the human, get to work the action you do a much better job than a semi-auto action that relies on the minimal .22 cartridge for its power source.

Were it me, I'd buy a Henry lever action .22 rifle. I love mine. If you need it to be more packable, simply remove the stock. It's only one screw. If you want takedown to be tool-less, replace that screw with a thumbscrew from the hardware store. It's a standard 10-32 thread, 1.65" long. I happen to have one sitting here in my hand, in case you're wondering ... I was just installing a tang sight on my Henry .22 (model H001T) today.