I will assume you do understand that you must go through a lot of paper-work, question answering, and signature work, before you can purchase your rifle. They must perform a background check by law to make sure that you are mentally competent and mature enough to own a firearm. Not only that, they want to make sure you aren't a fugitive from justice and you aren't a person with anger management problems or on any type of drug...
Besides that. If you go to Wal-Mart the manager of the store will escort you to the door. Once there, they will give you a firm hand-shake and a good-bye and send you on your way with your firearm. At any local gun-shop, after the paperwork they hand the gun to you and send you down the road.
If you purchase a firearm new, it will come with a box. Make sure to ask for it, because if they dont have a box for you then odds are that you aren't purchasing a new firearm. In the case of a used one, they usually don't come with a box and you are buying the firearm as is. They usually dont come with much of a warranty this way, unless you can contact the previous owner and he can give you some background on where the warranty stands.
A soft or hard case for casual carry to and from the field must be bought seperate in almost all cases.
And as always, you must be 21 years of age to purchase a high-powered firearm or pistol.