come to colorado and go to the community college in Trinidad, the gunsmithing school there was started by P.O. Ackley and is one of the best in the nation. After that it's coming up with the money to get all the tools and getting a reputation and client list good enough to make money at it.
the first thing I would do is take a intro to machine shop class and get to know your tools , it'll make the accutal gunsmithing school easier on you and your teacher
James Jones Question is a good one there is a big difference in training between a gunsmith who builds guns and one who just replaces parts. Although Their is a need for both in the industry. Can you get any training from your Grandfather before his retirement? you could have him sponsor you as an apprentice and get reduced tuition for the machine tech. training as well as other help with wages and L&I insurance.
here are some links to look at. Apprenticeship Programs
Have you been watching the sons of the guns? Going by the smiles on their faces, they just have too much fun doing what they do, and I envy them. But then, who wouldn't? I do have the highest amount of respect for Will though. In my opinion, he is also one cool-*** dude!
It has me fantasizing about getting into the kind of work that they do down there. But at my age, when the reality checks kick in, I realize those thoughts amount to nothing more than pipe dreams. I do make/shoot my own reactive targets though (staying absolutely within what the law allows). I can personally verify that big ones make for big smiles!
Anyways, if you are still young (and mechanically inclined), GO FOR IT! But you need to learn as much as you can, so you can be as good as you possibly can be. It is a very highly competitive line of work, because there are a lot of people who want in.
An apprenticeship with your grandfather would be an excellent way to start because of the
experience he should have and he would probably be happy and proud to pass own his skills
to a family member.
If he has been doing it for a long time he is used to building a lot of his own tools which will
help in future projects.
My recommendation would be to try and talk him into teaching you while closing down his
gunsmithing and letting you take it over. It would be a win win for both of you.