Coefficient of Expansion? WHAT?

Coefficient of Expansion! You know, you've heard of it..... COE? Bullseye vs. Effetre vs. NorthStar

When I took my first class I used Uroboro. While reading and picking up tidbits about the different COE's I read that Bullseye was the best glass for beginners. It seemed to be a bit more stiff which was good for someone new to lampworking, especially until they began to understand how to manipulate molten glass, gravity and heat.
I have a a tiny bit of Bullseye, a little bit of Effetre, a tiny bit of Vetrofond and one lb of Boro. Why do I have only 1 lb of Boro you ask? I have no clue other than it sounded like a great deal!!!!   UGH!!

Here are two charts: COE chart and a Melting Point for Metals Chart

COE 90 : Bullseye, Uroboros

COE 96: System 96, Uroboros 96

COE 104: Effetre, Vetrofond, Lauscha, Creation Is Messy (CIM), Striking Color,  Troutman Art Glass (TAG), Reichenbach, Olympic Color, Double Helix, ASK,

COE 32.5-Borosilicate: NorthStar, Pyrex, TAG,