From the Custom and Border Protection Office.:
Most firearms are restricted and / or prohibited from entering Canada and/or require licensing and registration. The Canada Border Services Agency is responsible for deciding whether to let a non-resident bring a firearm into Canada. As a general rule, non-residents may bring a non-restricted rifle or shotgun into Canada for approved purposes such as hunting, target shooting, wilderness protection or in-transit movement by a reasonably direct route to another point outside Canada. Restricted firearms (mainly handguns and some semi-automatic long guns) can not generally be imported into Canada.