Here are some pictuers of my Long Gun air cannon. They are not complete,yet. But they are what I am working on. I made them with a program called bCAD. ver 4.3 I got it from this link. Let me know if you have a problem getting it to install.
This is a rendering of the Long Gun. It does not show the barrel ,yet.

This is a rendering of the Barrel End of the Long Gun.

Here is a rendering of the Valve End <of back>of my Long Gun

I will be updating this page soon and adding more CAD drawings throughout my web site.