Above is a rough list of common barrel materials used today in the Nerf Internet Community. Always choose which barrels fit your foam best, instead of finding foam to fit a specific barrel material. From general knowledge, you'll want your foam to be tight in your barrels for springers, and loose for "air" blasters.
All Part numbers are associated with McMaster.com
If there is anything that's available online you'd like to add to this list, please let me know.
Disclaimer: These measurements are not exact. A lot of the materials specified vary greatly (ID) depending on a number of factors. It's always best to check them with a set of calibers to ensure the size.
Downloadable Word Document
(For copy/pasting part #'s)
Edited by Ryan201821, 26 July 2012 - 03:05 PM.