Acquiring a firearm legally is a ridiculously bureaucratic process where you must submit to psychological evaluations by the military and "justify" your "need" to own a gun. If you manage to get approved by that long process, your reward is an extremely limited selection of revolvers chambered in weak calibers that you can't carry with you outside your home or place of work. The weapon must be registered in a military database and tied to your name and those soldiers can suddenly decide to drop by and inspect your gear. There is a limit to how much ammunition you can purchase per year, so the only way you can practice with the guns is by making your own rounds. You can't even transport your weapon from place to place without notifying them and acquiring some kind of permit. Alternatively, you can become a gun collector who can own everything but can't legally fire any of the weapons, not even for practice.

Criminals don't care about gun laws. They just purchase weapons from the black market, no background check or psychological evaluations or anything. Burglars used to consider the risks before breaking into a home, but now they're sure they will be unopposed. Drug traffickers are much better armed than the police force that ought to stop them and have become so powerful in their domains they could be considered parallel states, with laws, judges and everything. Ironically, they often stop smaller crimes like robbery from happening because not having a safe environment for people to buy drugs in hurts their profits; photos of graffiti messages warning criminals they'll be killed if they get caught robbing people can be found on the internet. The entire disarmament thing assumes the police will do their jobs and keep people safe, but the police won't even enter these areas because they're outmanned and outgunned. That's why the government felt the need to use the military in order to regain control of Rio de Janeiro. They used armored vehicles to fight against people who are technically citizens of their own country.

Don't ever let the government take your guns away.