1. So what?
Metal detectors, X-rays, etc...
2. I could certainly hide them in a boat, train or car though.
Sure. I mean, it's not like boats, cars, and trains between the two countries aren't searched for drugs, which are much easier to conceal and require a far smaller amount to be profitable. I mean, how much money would you need to make just to pay for the cost of shipping? How many bullets would you need to sell?
3. I'd just line the chassis of my car with them. good luck metal detecting that. Why am I walking through the dessert? Did you ban vehicles as well?
Sure, you could. Drug runners probably do it all the time. But how many bullets could it hold? 2, 3 thousand? Current price of an AR-15 bullet is about $0.41/bullet. So you could, potentially, get like 2 grand for the lot. (inflated prices and what-not) How much of a profit is that? Would it even be worth it?
As for $500 a bullet, where did you get this? They already get the no-tax discount advantage, by being contraband. Now all I need is a corrupt arms dealer and some organised criminals. Making ammo is quite easy. Making guns, much harder.
Oh I just pulled a random number based on the cost of illegal drugs. Not sure what the price would be but you'd have to make a good profit for it to be worth it.
As for vehicles... have you ever SEEN our southern border? Most of it is a desert filled with impassable terrain, monitored by helicopters. It's not easy and alot of illegals are forced to make the journey on foot. And die.
I mean, you could make it a few times but eventually you'll get caught. And vehicles are way easier to track in the desert than people.
There is only one way to stop gun crime in America. You have to get rid of #2A. If you don't do that, forget anything else.