[ScottRiqui]

From the atf.gov site:

May aliens legally in the United States buy firearms?
An alien legally in the U.S. may acquire firearms if he has a State of residence. An alien has a State of residence only if he is residing in that State and has resided in a State continuously for at least 90 days prior to the purchase. An alien acquiring firearms from a licensee is required to prove both his identity, by presenting a government-issued photo identification, and his residency with substantiating documentation showing that he has resided in the State continuously for the 90-day period prior to the purchase. Examples of qualifying documentation to prove residency include: utility bills, lease agreements, credit card statements, and pay stubs from the purchaser’s place of employment, if such documents include residential addresses.

See also Item 5, “Sales to Aliens in the United States,” in the General Information section of this publication.

[18 U.S.C. 921, 922(b)(3), (d) and (g), 27 CFR 478.11 and 478.99(a)]