Those things are rather cool aren't they? Although if one was stuck on a remote island in the middle of the Pacific, the original .22 Hornet bolt-action type might be more functional, to put say, goat on the menu. But then you would have less ammo, so I could see the sense in a .22 rimfire.
https://en.wikipedia.org/wiki/M4_Sur...ival-Rifle.jpg
And the AR7 looks more comfortable to hold.