If you are in or near North Carolina the link below to Montgomery Community College may be a good option:
http://www.nragunsmithing.com/montgomery.htmlSome of the instruction is first class especially the class below by a long time NBRSA competitor:
Bolt Action Accurizing - James Messer
Learn precision action work, threading, chambering, other accurizing techniques. Improve performance of bolt action rifles from muzzle to breech. Bedding methods will also be covered. (Working knowledge of lathes required.)
Actually one should take machine shop on, Lathes, Milling Machine and Welding before entering into a gunsmith school as a pre learning experience.