As an American, if you accidentally brought a gun to the Canadian border crossing and just remembered it when they asked you if you have any weapons in the car, are you probably going to prison for that mistake?
I am a Canadian, but cross the border a fair number of times for day trips each year. More often than not, I like to pick up my favorite alcohol on my way back. Since it was only a day trip, I get to pay the taxes and duty. This is important only to point out I have to go inside, queue up behind other who are dealing with stuff like hand guns, duty owing etc.Now I have been behind people with hand guns a few time. Here is what I have learned. Now remember I am not a customs agent, so these are just my observations of the interactions with others.First off, yes everyone is correct, DECLARE you firearms, ammunition and explosives. If you do not declare them, and they find them, you are in a TON of trouble. If you are not 100% sure if your hand gun is in your trunk, tell the customs agent exactly that, “I think I took my gun out of my trunk, but I am not 100% sure right now.” They will look, if it is there no problem, if it isn't there even less of a problem. Now if you do have a hand gun, and declare it here is what I have seen happen a few times. Customs will take your gun into their control. It will be tagged and received into inventory. As a courtesy, Canada Customs will hold your hand gun at the border crossing you entered at and issue you a receipt. When you level Canada back to the USA you cross at the same customs point stop off at Canada Customs, give them the receipt and they will give you your gun back for you to take with you back into the USA. I am not sure of the maximum amount of time Canada Customs will hold your gun for you, but they are usually pretty easy going.Now some advice, When you get to the Customs office, you are already inside Canada. If you are carrying a gun, you have committed a pretty serious offense, but like USA ICE/INS the customs officers are there to protect the sovereignty of their country they have no interest in giving you a hard time, unless you MAKE them want to. So to this end, IF you cross the border and find you have something illegal to import and you did not declare it you are in the wrong. Work with the border patrol, they WILL work with you. I know this much from 1st hand experience going into the USA with Cuban cigars, which at the time was a felony to import into the USA. When confronted with the cigars I was to say the least surprised. I knew the box they were in was something I had thrown in the back seat the night before. I know I had Cuban cigars in that box 3 years ago, but I had thought they were all gone. I was wrong to the count of 2. Well enough to say I was going to get the cigars taken away from me. If they were not dried out they would be worth about $75.00 each. When I was told they would be seized I replied with, “Of course, I understand.” and then again apologized for violating US Law. The end result was I lost two cigars, 20 minutes and had to fill out a ton of paperwork. That was it.Now on the Canadian side I was in line behind some American who was yelling at the border officer about how, holding his gun and him having to cross into the USA at the exact same customs point in order to get his gun back, unacceptable that was to him. At one point threatened to take the officers to court and sue them. That is when an RCMP officer grabbed the guy by the neck, walked him briskly to the south facing window, so fast the guy face hit the window. The white posts were pointed out to him (The border between Canada and the USA) and that he was already in Canada, with a gun, and if they so desire he could be charged then and there with attempting to smuggle fire arms into Canada. The guy because very quiet after that.No one expects every person that crosses the US Canada border to know all the rules, and know what the up to date rules are. The trick to making your crossing easier than you ever imagined is be calm, helpful, honest. And don’t give the customs agents hell, they are doing their jobs. If you want to yell at someone, yell at your Member of Parliament, or Congressmen, they write the rules.