A friend of mine was going to Canada and as a retired cop always had a handgun with him. He "forgot" to remove it from his trailer and leave it at home. When he arrived at the Port of Entry was asked about guns and fessed up to having forgotten to remove the gun. Despite that, his gun was seized and he was denied entry into Canada. He thought he was going to jail and still can neither get his gun back or return to Canada. Another friend entering Canada spent four hours at the Port while their truck and trailer were searched.
That said, when we went to Canada this summer, even though they were aware I am a retired cop, we passed through in minutes without incident. Good luck!