You may ship restricted firearms, non-restricted firearms and prohibited handguns from one Canadian location to another Canadian location if you use the most secure method offered by Canada Post that requires a signature upon delivery. Prohibited firearms, other than prohibited handguns, and firearms being shipped across the Canadian border, must be shipped by an individual or carrier company licensed under the Firearms Act to transport those classes of firearms.
You are required by law to ship firearms unloaded and in a safe and secure manner to deter loss, theft and accidents.
-- RCMP
A firearm cannot be shipped to another country by Canada Post. Instead, a carrier company licensed to transport firearms under the Firearms Act must be used.
-- RCMP
Shipping by Post
16 An individual may ship a firearm by posting it only if
(a) the firearm is a non-restricted firearm, restricted firearm or prohibited handgun;
(b) the destination is within Canada; and
(c) the firearm is posted using the most secure means of transmission by post that is offered by the Canada Post Corporation that includes the requirement to obtain a signature on delivery.
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http://laws-lois.justice.gc.ca/PDF/SOR-98-209.pdf