Last Updated: Jul 19, 2016 Views: 28
Check out Mickelsen's article on lampworking using soft glass. He includes information on COE and provides a list of suppliers at the end of the article.
Also see the warmglass.com website's information on COE: http://www.warmglass.com/COESummary.htm
According to the glasscolor.com website, which lists COEs for many different glass makers, there are one or two with lower measured COEs than Bullseye:
If you need more technical/background information than this, I'm attaching a bibliography of materials on COEs.