Crossbows would be the ideal, in canada at least, seeing that one dosnt need a lisence to own one hur, the ones with collapsible limbs are especially cool. saw one at princess auto a few weeks ago, figuring it was a kids toy I casually asked
the draw weight, 150lbs! barely over a foot an a half long! more then enough to take down big game even though in a transitory situation taking big game would be a terrible idea..
as for slingshots, if your gonna wanna get one then refurbish it with some theraband, preferably gold. Its a physiotherapy elastic thats durable and customizable in length, strength and power. Altho one would want to be carrying around steel or lead bearings as a more efficient round over rocks.
Slingbows are a pretty cool concept and can be easily made from a regular slingshot with the addition of a whisker biscuit.
an atlatl is more of a catapult then a sling, the grooved stick acted as an extension of the arm allowing you to gain more momentum in your throwing of the spear, neat little tools, but the amount of specifics and practice needed makes them somewhat inefficient when needed immediately for survival.
I posted this mainly because of the number of people I saw who traveled with a walking stick, the only addition to your gear is a couple leather straps, takes up no extra space except on the top of yo stick, and your ammo can be literally be anything you come across.
