From a quick google search (you couldn't do one...WHY?) it seems you don't need any sort of permit to own a shotgun/rifle. You do need to be 21 for pistols, though.
1: Go to gun store, ask to look at a gun.
2: Guy takes it off the wall, or out from the counter, hands it to you.
3: You ask to buy it.
4: He gives you paperwork, they run a background check on you.
5: You might have like a 72 hour hold, before you can actually walk out with it. Most states don't have holds on rifles, though... only pistols.
Enjoy, faggot.