Go with Westjet. Air Canada charges an extra $100 or so for having a firearm as part of your baggage. Firearms must be unloaded and locked in a hard sided case ammo is not permitted in the case. Ammunition may travel in your checked luggage maximum 11lbs (5kg), in a hard sided case in original packaging (no loose ammo).
Get to the airport a little early. Check in at the counter and declare that you are traveling with firearms/ammo as your checked luggage. Sign the declaration form. The agent may not be familiar with the proper form and hand your an armed officer / prisoner transport form. If you are given the wrong form ask for the proper one. Bag will be tagged ammo sticker may be attached to bag containing ammo. You will usually be directed to take your firearm & bag containing ammo to the oversized luggage drop. Present your boarding pass and declaration form to person at the oversized bag screening. Bag may be x-rayed in front of you depending on the airport. Proceeded as normal with rest of the flight.