Not all projectile weapons use bullets. Some of them use strings, cables, and plain old upper body strength to propel small, pointy objects at zombie skulls. This section lists all projectile weapons that are not propelled by gunpowder.
[edit] Bows
Unless your name is Ted Nugent, Green Arrow, or John Rambo, it’s not recommended that a bow be used in a survival situation, especially one involving zombies. The advantages of this weapon (they’re silent, the ammo can be reused) are outweighed by its flaws. They require a lot of training and strength to use effectively (and even then, try getting a headshot against a moving target), they have a limited range, they have bulky ammunition, they have a slow fire rate, and if you get injured, you may be unable to use your main weapon. There’s a reason why guns replaced bows on the battlefield - it requires much less training to use a firearm than a bow and arrow. And no, don’t even try to put an explosive tip to the weapon. The weighted arrow will probably only fly far enough to blow you into bite-sized nuggets. In lieu of exploding or armor piercing arrows, try using lit fire arrows. They don’t need headshots and ensure a slow but guaranteed kill. The usual benefits and limitations of using fire apply.
[edit] Crossbows
The main advantage of a crossbow over a rifle is that it is extremely quiet. When one realizes how well a zombie can hear a distant gunshot, this makes the weapon very useful for someone looking to evade zombies instead of fighting them. Also, it eliminates the main problem that the traditional bow and arrow has as a survival weapon: it does not require a great deal of strength and training to use. And again, the ammo can be retrieved from dead zombies. The crossbow also has a surprising amount of stopping power, capable of stopping large boar in one shot, depending on the strength of the crossbow and the size of the bolt. Several modern crossbows also allow for the addition of scopes or laser sights. However, it still has the slow fire rate, bulky ammunition, and limited range that the bow suffers from. Consider the crossbow as a weapon if your survival plan involves evading the zombies rather than fighting them outright.
[edit] Sling
A sling is a projectile weapon typically used to throw a blunt projectile such as a stone. A sling has a small cradle or pouch in the middle of two lengths of cord. The sling stone is placed in the pouch. Both cords are held in the hand, then the sling is swung and one of the two cords is released. This frees the projectile to fly on a tangent to the circle made by the pouch’s rotation. The sling derives its effectiveness by essentially extending the length of a human arm, thus allowing stones to be thrown several times farther than they could be by hand.
The sling is very inexpensive, very lightweight, easy to build, silent, and you can find ammo for it practically anywhere. It has historically been used for hunting game and in combat. The sling was the weapon of choice for shepherds in the field due to its usefulness for fending off other animals, and an expert could easily bring down a lion with one well-placed stone. The most famous story of the use of a sling is the story of David and Goliath, in which the child shepherd David, armed with only a sling, defeats the giant warrior champion Goliath with a well-aimed shot to the head.
While this may seem like perfect qualifications for use against zombies, there are important disadvantages you need to consider first. A sling is not as accurate as a rifle, and even with years of practice even an expert slinger will have considerable difficulty hitting a human head at long range with enough force to do serious damage. So unless you are already an expert with the sling, it’s probably better to just use a gun.
[edit] Slingshot
Made famous by the likes of Dennis the Menace and Bart Simpson, the slingshot uses the same principle as the sling. The forked Y-shaped frame has two rubber strips attached to the uprights, leading back to a pocket for holding the projectile. While easier to use and far more accurate than the sling, these advantages come at the cost of power and range. A slingshot barely has the power to bruise the skin on a zombie’s head, let alone damage its skull. If you were to use it against a zombie, all you would do is get it’s attention.
[edit] Blowgun
Poison has no effect on the undead, so forget this one entirely.