According to GA law, you would have to be 18 to carry a handgun at work. A rifle might be legal, but it's kind of hard to do any kind of productive work with a rifle slung on your shoulder. An exception might be a cap and ball revolver, have to do more research on that:
O.C.G.A. § 16-11-132
Copyright 2013 by The State of Georgia
All rights reserved.
*** Current Through the 2013 Regular Session ***
TITLE 16. CRIMES AND OFFENSES
CHAPTER 11. OFFENSES AGAINST PUBLIC ORDER AND SAFETY
ARTICLE 4. DANGEROUS INSTRUMENTALITIES AND PRACTICES
PART 3. CARRYING AND POSSESSION OF FIREARMS
O.C.G.A. § 16-11-132 (2013)
§ 16-11-132. (For effective date, see note.) Possession of handgun by person under the age of 18 years
(a) For the purposes of this Code section, a handgun is considered loaded if there is a cartridge in the chamber or cylinder of the handgun.
(b) Notwithstanding any other provisions of this part and except as otherwise provided in this Code section, it shall be unlawful for any person under the age of 18 years to possess or have under such person's control a handgun. A person convicted of a first violation of this subsection shall be guilty of a misdemeanor and shall be punished by a fine not to exceed $1,000.00 or by imprisonment for not more than 12 months, or both. A person convicted of a second or subsequent violation of this subsection shall be guilty of a felony and shall be punished by a fine of $5,000.00 or by imprisonment for a period of three years, or both.
(c) Except as otherwise provided in subsection (d) of this Code section, the provisions of subsection (b) of this Code section shall not apply to:
(1) Any person under the age of 18 years who is:
(A) Attending a hunter education course or a firearms safety course;
(B) Engaging in practice in the use of a firearm or target shooting at an established range authorized by the governing body of the jurisdiction where such range is located;
(C) Engaging in an organized competition involving the use of a firearm or participating in or practicing for a performance by an organized group under 26 U.S.C. Section 501(c)(3) which uses firearms as a part of such performance;
(D) Hunting or fishing pursuant to a valid license if such person has in his or her possession such a valid hunting or fishing license if required; is engaged in legal hunting or fishing; has permission of the owner of the land on which the activities are being conducted; and the handgun, whenever loaded, is carried only in an open and fully exposed manner; or
(E) Traveling to or from any activity described in subparagraphs (A) through (D) of this paragraph if the handgun in such person's possession is not loaded;
(2) Any person under the age of 18 years who is on real property under the control of such person's parent, legal guardian, or grandparent and who has the permission of such person's parent or legal guardian to possess a handgun; or
(3) Any person under the age of 18 years who is at such person's residence and who, with the permission of such person's parent or legal guardian, possesses a handgun for the purpose of exercising the rights authorized in Code Section 16-3-21 or 16-3-23.
(d) (For effective date, see note.) Subsection (c) of this Code section shall not apply to any person under the age of 18 years who has been convicted of a forcible felony or forcible misdemeanor, as defined in Code Section 16-1-3, or who has been adjudicated for committing a delinquent act under the provisions of Article 6 of Chapter 11 of Title 15 for an offense which would constitute a forcible felony or forcible misdemeanor, as defined in Code Section 16-1-3, if such person were an adult.