Here's my 2 cents.....I have harvested more small game with my break-barrel Winchester .177 pellet rifle than with all of the firearms I own put together. I use Copperhead lead hunting pellets, and I have consistantly taken squirrels and large rabbits at 25 yards or more.

I have owned/tried various BB guns, and they are fun to shoot cans with but as a survival tool, they don't have the range or power to justify the weight. I have a Daisy BB gun, and I use it to keep squirrels from building nests in my maple trees. The BB just stings them.

I also cannot recommend any of the short-barreled CO2 pistols I have tried for three reasons: they are extremely short range, they are hard to aim accurately, and powerlets are big and clinky and when they're gone the pistol becomes a paperweight.

My advice echos what a couple of others have said: If you can't afford a good pellet gun right now, buy a good quality hunting slingshot. You can use cheap marbles as ammo and practice with bags of round hard candy. Here is a picture of a folding Marksman hunting slingshot like the one I have carried for many years in my rucksack. You can buy them online for under $10. I also carry a spare powerband ($3.50) and several good quality regular rubber bands in an altoid tin in my small backwoods kit so I can make an emergency slingshot from a tree branch and use round river gravel as ammo.

Practice is the key word. You be amazed at how good you can be with a slingshot.