If you are talking the old fashioned Red Ryder style single **** Daisy BB gun, it will not kill squirrels, let alone rabbits.
BB guns aren't very accurate either-steel balls in smoothbore barrels-which is why bb gun tournaments are had at FIVE meters. Pellet guns with rifling are far more accurate
there are several kinds
barrel **** spring air guns
probably the best choice-they are durable and accurate and fairly easy to **** short of the magnum jobs. They will last for years if maintained. Some spring jobs use side levers or under levers rather than the barrel and might be slightly more accurate but since those levers are shorter than the barrel, the leverage is less and they are harder to **** and invariably more expensive for a barrel break gun of the same quality
multi pump Pneumatics-variable power is the selling point-2 pumps for plinking-8 to ten for hunting. disadvantages-multiple pumps per shot and these rifles have Valves which are more likely to fail than a spring air gun. IN a springer its the expansion of the spring that pushes air and then the pellet while in pneumatics its compressed air
single stroke pneumatics-advantages-very accurate, one stroke cocking
disadvantages-valves again. mainly these are for target shooting and are expensive
Pre-charged Pneumatics-these are the rifles and pistols used to win the olympics and dominate serious hunter's air gun arsenals. They often can be shot several times before recharging. My son has one that can kill coyotes and can be shot many times in a row. The disadvantage is cost and the fact you need a compressor, or an expensive pump (300 average) or a scuba tank and a place to charge it to run these things. Plus again they have valves
CO2 guns. sort of like PCPs but you don't need a compressor. some use throw away 12 g cartridges (most common) and others use the refillable tanks that paint ball guns use. these are good for rapid fire pistol air guns
the disadvantage is buying co2 cartridges or having to go to a depot to have the canisters filled, plus their durability is less than a spring gun. Plus the point of impact changes depending on the outside temperature that the gun is used in. They tend to give the best performance for the price though even though the C02 cartridges do increase operating costs. The refillable canister guns are cheaper in the long run but they are much more limited in number and normally limited to air rifles since the canisters are generally too big for pistols
having owned lots of all the above, for the money I'd buy a decent break barrel pellet gun. Not much to break, accurate, quieter than PCPs or Co2s, more durable and if you get a 600-700 FPS (medium power) it will kill squirrels and rabbits and won't be too hard to ****. My son was whacking starlings with one at age 8 and he was a very small 8 year old
