The answer is nothing has changed in regard to U.S. law and you must go through an FFL to purchase a firearm and export.
Purchasing a firearm from a nonlicensee to possess in the United StatesThe deal must go through an FFL and you can't take possession. The FFL must do a permanent export and ship the firearm to Canada. This includes firearms given as a gift, won at a shoot, or found along the side of the road!
A nonimmigrant alien generally MAY NOT purchase a firearm from a nonlicensee to possess in the United States. If you violate this prohibition, you could receive a maximum of 5 or 10 years of imprisonment, depending on the violation. If you have questions regarding possible exceptions to this prohibition, contact the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF).
The rule for U.S. citizens in regard to transfering a firearm:
Q: To whom may an unlicensed person transfer firearms under the GCA?As your not a resident of the state, no sale. FFL REQUIRED.
A person may sell a firearm to an unlicensed resident of his State, if he does not know or have reasonable cause to believe the person is prohibited from receiving or possessing firearms under Federal law. A person may loan or rent a firearm to a resident of any State for temporary use for lawful sporting purposes, if he does not know or have reasonable cause to believe the person is prohibited from receiving or possessing firearms under Federal law. A person may sell or transfer a firearm to a licensee in any State. However, a firearm other than a curio or relic may not be transferred interstate to a licensed collector.
[18 U.S.C. 922(a)(3) and (5), 922(d), 27 CFR 478.29 and 478.30]
A must read...
Nonimmigrant Aliens Purchasing Firearms and Ammunition in the United States
A listing of Firearm Dealers who will do the paperwork and export a firearm to Canada.
For those who have no intention of purchasing a firearm, but just want to visit the states with a firearm, the process takes several weeks.
The procedure can be found here.
VISITORS TO THE UNITED STATES - ATF Form 6NIA