Rifles and shotguns can be purchased across state lines. Since they're being kept in Florida, I don't see an issue.
The sticky part involves handguns:
If a person maintains a home in 2 States and resides in both States for certain periods of the year, he or she may, during the period of time the person actually resides in a particular State, purchase a handgun in that State. However, simply owning property in another State does not qualify the person to purchase a handgun in that State.
[27 CFR 478.11]
If you have residence
in Florida, you can buy handguns there. Most dealers will require a Florida driving license or state ID with your Florida address.