There are a lot of rules and procedures for importing firearms. First of all, you need to have a Canadian Acquisition and Possession license either at the timer you import them or shortly thereafter. Also, if you are transporting the firearms by car, you also need to check the law in every US state you pass through or you could have a lot of friction in a traffic stop if you aren't transporting them legally according to the laws of that state. Best to do your research on this one well beforehand.
