Homemade Airgun Reference

Common Pipe Sizes
When building an airgun, it is important to know your internal diameters for calculating volume or deciding if a pipe would be useful as a barrel. Outer diameters come in handy with the actual construction of the airgun. Here are some charts that you might find useful:

Rigid Copper Pipe
One of the best materials out there for homemade airguns. It is easeily obtainable, relatively easy to work with, and handles a good amount of pressure. For information on how to work with copper pipe, check out this page (large pdf file, may take some time for you to download).

PVC Pipe
PVC is probably the easiest pipe to work with and is much cheaper than copper. Its major drawbacks are that it doesnt handle much pressure and it becomes unsafe to use at extreme temperatures. That being said, airguns made from PVC are cheap, fun, and quick to put together. Just keep the pressure low (50 to 150 psi depending on the pipe used) and dont use it below 50 degrees or above 100 degrees. For practical purposes, PVC comes in two flavors - schedule 40 and schedule 80. Schedule 40 is the most common and works best for most applications. Schedule 80 is designed to handle more pressure and is great when your airgun needs to withstand greater pressure and/or abuse. Be sure you do not use cellcore pipe or dwv fittings as they are not pressure rated.

PVC pipe is jointed to fittings by a process called solvent welding. For a good demonstration on how to properly solvent weld pipe, go here. Be sure you wait the recommended curing time before pressurizing your project!