J'ai trouvé ça ;
ery simply, no, they can not.
In order to purchase a firearm in the US you must be a resident of the state in which you are buying it, and able to prove that residency. As a tourist is not a resident of the state, they are unable to purchase firearms.
There was previously an additional requirement that non-citizens had to have been a resident of a state for 90 days before they could purchase a firearm in that state, but that additional condition was removed earlier this year.
Even if you could purchase a firearm, doing so for "travels around the United States" would be troublesome as gun laws vary from state to state, so what is legal in one state could be illegal in another.
he following list of prohibited persons[9] are ineligible to own or use firearms under the Brady Handgun Violence Prevention Act.[10]
Those convicted of felonies and certain misdemeanors except where state law reinstates rights, or removes disability.
Fugitives from justice
Unlawful users of certain depressant, narcotic, or stimulant drugs
Those adjudicated as mental defectives or incompetents or those committed to any mental institution and currently containing a dangerous mental illness.
Non-U.S. citizens, unless permanently immigrating into the United States or in possession of a hunting license legally issued in the United States
Those who have renounced U.S. citizenship
Persons convicted in any court of a misdemeanor crime of domestic violence (an addition)
Persons under indictment for a crime punishable by imprisonment for more than one year are ineligible to receive, transport, or ship any firearm or ammunition
En gros ça a l'air que tu dois avoir ta citoyenneté et aussi résider dans l'état que tu achètes ton arme si c est à un dealer , ou sinon p-e un permis de chasse US te donne droit.
Autre lien Wikipedia ;
http://en.wikipedia.org/wiki/Gun_laws_in_Vermont