This info could be handy to someone now or in the future is a shtf scenario. As long as there are guns there will be a need for gunsmiths.
Wanting to make modifications to your fire arms or looking to make a living as a gunsmith, Off the grid news has an awesome piece on survival gunsmithing.
Survival Gunsmithing Anyone Can Do
http://www.offthegridnews.com/2012/02/20/survival-gunsmithing-anyone-can-do/