In order to buy a long gun in Florida, the state that you reside in must allow you, or not prohibit you, from purchasing a firearm out of state, except for bordering states (AL and GA). Many states will only allow their residents to purchase in bordering states, some do not prohibit their residents from purchasing long guns in another states.

Go here to see if Indiana allows its residents to purchase long guns out of state.
http://www.atf.gov/publications/fire.../29th-edition/

If you have dual residency (you or your parents (If you are still considered a dependent) own a house in Florida and Indiana and actually live half the year here and half there) you can buy a long gun or hand gun in Florida.