Wayne,

Early war Confederate regiments often had Volunteer in their title because they were truly an all volunteer unit. Even post-bellum, the veterans would put the term volunteer into their unit's official designation when it was inappropriate to do so.

Below are links that may help you.

Confederate
http://www.tngenweb.org/civilwar/csainf/vaughn.html

http://www.tngenweb.org/civilwar/csainf/brown.html

Federal
http://www.tngenweb.org/civilwar/usainf/usa3inf.html

I hope this helps.

Respectfully,

Gerald D. Hodge, Jr.
War Between the States Historian
Historian: 39th Georgia Volunteer Infantry Regiment
http://39thgavolinfrgt.homestead.com/39thHomepage.html