The question asked on the form 4473 in 11 (a) is: Are you the actual purchaser of the firearm? If you read the instructions for question 11(a) on the back of the form, http://www.atf.gov/forms/download/atf-f-4473-1.pdf-
it tells you that if you are buying it for yourself- OR LEGITIMATELY BUYING IT AS A GIFT FOR A THIRD PARTY- it is not a Straw sale.
Translation. Bobby gives me the money to buy a gun for him. Straw sale.
Bobby is my Best Man at the wedding, and I want to GIVE him a gun as a Groomsman's gift. Federal law (state law, yer own your own) says that you can do that, so long as Bobby and I reside in the same state, and I do not have cause to believe Bobby is prohibited from possessing a gun.
And neither Arizona nor the Federal government has any provision to "register" a gun in anybody's name. The dealer retains the form 4473 at their premises for 20 years.