So, I requested a quote from a local testing lab here in Chicago in an effort to discover the composition of the metal used in creating these chairs. It's very important to re-create the 'bounce' and also, I'd prefer the chairs not snap in half in someone of 'size' sits in one and decides to test out the limits of the spring action. If interested, you can follow my progress on my new site. www.steelglider.com
There is a blog section where I'll post results of my activities. Thanks again for all your help!