18 USC 922 (a)(3), (a)(5) and (b)(3) are the Federal laws governing state of residence requirements for firearms transfers. In summary, with the exception of inheritance transfers (when someone dies):
1. Firearms transfers between private parties with no FFL (Federal Firearms License) involvement can only legally happen between two persons who reside in the same state, long gun or hand gun.
2. An FFL (which the pawn shop should hold) can transfer a rifle or a shotgun to a resident of any state so long as the state laws of both the FFL and the person receiving the long gun are followed.
3. An FFL can transfer a firearm other than a rifle or shotgun only to a resident of their own state.
If you purchase a firearm from a private party that does not reside in the same state as you, the firearm must be transferred through an FFL, and if the firearm is other than a rifle or shotgun, that FFL must be in your own state of residence.
If you purchase a firearm other than a rifle or shotgun from an FFL in a state other than your own state of residence, they must transfer the firearm to an FFL in your own state of residence for transfer to you.
Individual state laws may be more restrictive, those are only the Federal requirements.