Nah, just a Form 6 like everywhere else in the U.S.
It helps to belong to a club in the U.S., and to be a member of USPSA is almost a must as it gives you a written invitation to USPSA matches. That, along with a club invitation (which they are very cordial to do) is your ticket to ride.
Tonawanda is real easy. I go every month, and virtually never have a problem at the border. They are used to us going for the monthly matches, so most of the guards are aware of the situation. If they send you to secondary, it is just a check of your Form 6 serial #'s aompared to your guns. Five minutes, and your gone!
One of the worst things in Ontario is the fact that they want a Form 6 copy sent before you get a border permit. Yeah, that's right, the Canadians want a copy of your AMERICAN paperwork before they will proceed! So, what do we do? Of course we send them a copy, and a few weeks later we get a border permit. What a hoot!
Like Black (fake GM by the way) says, just have all your paperwork in order, and they are usually very kind.