Just so you know, I have this.....
http://www.myus.com/
They forward packages to canada very nicely, worth looking into if you are working on a car, or just shopping around for great online "lower 48 shipping only" deals.
From their site:
Where can I find information about which types of merchandise are not allowed into my country?
The following list is a non-exclusive sampling of items that are either restricted, cannot be shipped or, depending on your destination country, may either require an import license, additional documentation and/or cause problems and delays during the customs review of your shipment:
"snip"
4. Firearms, weaponry and their parts: military, police and tactical equipment of any kind, including guns, gun replicas, gun accessories, gun components (magazines, clips and rail systems), ammunition, knives, swords, compound bows, crossbows, discharge weapons such as shock batons or stun guns, tooling for guns or gun parts, optical scopes, laser sights, night sights, night visions goggles, handcuffs and other restraints, surveillance equipment.