Widener’s has a web page and video Guide to Smokeless Powder (via email from Anne Taylor at Widener’s where I buy some of my reloading supplies). The basics are explained at a superficial but useful level:
Smokeless powder may be the most important component for any shooter who is reloading ammo and it’s probably the most complicated as well. With different characteristics and a ton of variables, gunpowder needs to be fully understood before you attempt to reload ammunition.
This guide will take you through the basics of reloading powder, show how all smokeless powder is not the same and demonstrate how the different characteristics of powder can make your reloads more effective depending upon your intended purpose.
I liked the video in particular (but check out the web page as well) because I have had people insist smokeless powder in open air will go up in a flash from a spark. My experience attempting to use it for recreational purposes in such a fashion was quite disappointing. This video is consistent with my experience. It’s tough to even ignite smokeless powder and, in open air, it burns slowly.