For Gun Control Act (GCA) purposes, a person is a resident of a state in which he or she is present with the intention of making a home in that state. The state of residence for a corporation or other business entity is the state where it maintains a place of business.
A member of the Armed Forces on active duty is a resident of the state in which his or her or her permanent duty station is located. If a member of the Armed Forces maintains a home in one state and the member’s permanent duty station is in a nearby state to which they commute each day, then the member has two states of residence and may purchase a firearm in either the state where the duty station is located or the state where the home is maintained.
[18 U.S.C. 921(b), 922(a)(3), and 922(b)(3); 27 CFR 478.11]