I trust my driving skills too. But that doesn't mean I'm not going to take simple precautions like wearing a seat belt. Although I have no problem forcing people to learn how to use a gun before allowing them to purchase them. It's very much like owning a car. It's very dangerous and requires responsibility.
Guns require some kind of maturity.
The practice would be to ensure that someone knows enough about guns not to shoot himself stupidely. But I'm not entirely sure. I haven't given it a whole lot of thought. The existing arguments I've made can extend to the bigger, more powerful guns, but the argument gets somewhat weaker. If machine guns are illegal, then the government would have less trouble subjugating people who only have handguns.