To answer the question more fully, the best way to become a real professional gunsmith is to attend a gunsmithing school.
These are trade schools or junior colleges that offer hard core gunsmith training by master gunsmith/instructors.
This typically takes at least 2 years and costs some significant money.
However, if you can graduate from one of the better schools like Colorado School of Trades, or Trinidad Junior College you'll have world class training which is recognized industry wide as the best.
A degree from a good school will get you a serious job interview anywhere.
These schools aren't internet or mail order rip-off Billy Bob "training".
If you're not stone cold serious, don't bother coming.
Here's a list of the available schools:
Colorado School of Trades
1575 Hoyt Street
Lakewood, CO 80215
Phone: 800-234-4594
Lassen Community College
P.O. Box 3000
Susanville, CA 96130
Phone: 530-257-4211
Modern Gun School
80 North Main Street, P.O. Box 846
St. Albans, VT 05478
Phone: 800-493-4114
Montgomery Community College
1011 Page Street
P.O. Box 787
Troy, NC 27371
Phone: 800-839-6222
Murray State College
One Murray Campus
Tishomingo, OK 73460
Phone: 580-371-2371
Pennsylvania Gunsmith School
812 Ohio River Blvd.
Avalon
Pittsburgh, PA 15202
Phone: 412-766-1812
Piedmont Community College
1715 College Drive
P.O. Box 1197
Roxboro, NC 27573
Phone: 336-599-1181
Pine Technical Institute
900 4th Street
Pine City, MN 55063
Phone: 800-521-7463
Trinidad State Jr. College
600 Prospect
Trinidad, CO 81082
Phone: 800-621-8752
Yavapai College
1100 East Sheldon Street
Prescott, AZ 86301
Phone: 520-776-2150