Part of it was crowdsourced to my fellow forumites, but a lot of that thread was just me, Google & Wolfram Alpha. You could probably still find it buried somewhere on the suggestions forum with that giant table of materials, material properties & sources.
Here is the thread where the initial !!Science!! on whether bolt weight made an impact on their lethality - [Dwarven Research: The Effect of Bolt Weight on Crossbow Performance](http://www.bay12forums.com/smf/index.php?topic=115683.0)