In writing about how to hunt with a blow gun it should be noted that virtually nobody should be hunting with a blowgun! That is unless they live in the depths of South America or Africa and grew up using blowguns, so know how to handle them. Blowguns can be and are dangerous, especially in inexperienced hands.
How can a blowgun be dangerous? The darts are very small and lightweight and there is no explosives involved. What are the hazards?
Blowguns do not kill with force, the darts kill with poison. All the blowgun does is prick the skin, put in a small amount of poison and then the animal's bloodstream takes it through the body and the animal dies, often of a heart attack. The most common poison used in South America is curare. A small prick with this and it can kill a human as fast as an animal, just touching poisoned darts can be dangerous.
How does primitive man manage? Very carefully and from a lifetime of conditioning and practice! The primitive hunter has been handling the toxins and over time builds up immunity, or dies. A person in the modern world doesn't have this biological resistant or the practice at handling the darts, they can kill themselves!
Still want to try using a blowgun for hunting? Here is what else you need to know and how to get started.
The number one thing to realize is that the longer the blowgun with the narrower the bore, the easier it is to shoot and the farther the range. This is because it is the compression from your lungs that propels the dart. The narrower the opening, the more force that can be built up. The longer the tube or gun, the straight the dart will fly. Just like with pistols and rifles, the longer the barrel, the greater the range.
You will need to keep the blowgun dry or you will have two problems, it will warp and the bore can swell shut, blocking the darts from being expelled properly. The darts need to be kept dry as well, but not as much as the gun (They are usually fire hardened and will not adsorb moisture as quickly)!
Practice with your blowgun using a target and non-poisoned darts. Up close to the target, the dart will frequently rise as it leaves the gun. After a few yards gravity kicks in and it starts to fall. Practicing at different ranges will let you know how close you need to be to compensate.
Do not try to use your blowgun on windy days. The darts are light and wind will effect them more than with lead bullets or even arrows. Always shoot at an angle and not with the wind blowing at you, the darts can come back and remember, a prick can kill!
Cook the prey well after hunting, most poisons are removed easily that way, and you have just killed using poison! Good luck.