All the legalistic shenanigans involving Harry Potter, Dolores Umbridge and Cornelius Fudge that kaffir describes above are due to the fact that Harry broke the decree on underage wizardry. That is to say, under-age wizards are not allowed to use magic of any kind outside the place where those skills are taught. It was nothing to do with the rules governing the possession of instruments capable of lethal force among the wider wizarding population.
If you have to draw parallels with the real world, then the parallel is to forbid minors from using weapons capable of lethal force. Child armies aside, I do not think there is a country in the world that permits children to use guns. Even the NRA is not that stupid.
J K Rowling has not given us a general ban on adults using wands for causing injury and pain by hexing and cursing. She has given us legislation against use of wands to inflict three, specific unforgivable curses. One is used to kill. Another is to inflict a lot of pain. The third is to impose control over the actions of an individual. Using any one of these will, in the HP universe, bring the perpetrator a life sentence in prison.
JKR's books, therefore permit residents of the HP universe to carry weapons capable of lethal force, but use of lethal force is enough to bring a life sentence in prison.
The equivalent is the situation in North America where citizens are allowed to carry guns, but the law forbids using them to commit murder.
I suspect that readers who uphold the right to bear arms will see support for their viewpoint in any book, while those who believe in gun control will find equally strong support for their viewpoint if they are selective in their reading of this book. Or any book.
That author's comments on defending oneself against government-directed soul-suckers are also misguided. British law permits use of appropriate force in self-defence, as does US law. It is up to the courts to decide what is "appropriate".
In the HP case, Harry used a spell which merely prevents attack without inflicting damage on the soul-sucker. He was charged with breaching the edict on under-age wizardry. It was proved that he was acting in self-defence, and he was acquitted, despite using magic before his 17th birthday.
In the case of Tony Martin, the courts decided that chasing the youths and then shooting them in the grounds of his house, as they ran away was excessive force. The Tony Martin case aroused a great deal of public sympathy, and I think the noder above fails to understand the complexity of the case in presenting it in this simplistic way.
A more common experience in British law is where a householder uses appropriate force, up to and including causing death by shooting, the law enforcement agencies choose not to bring charges against the property owner. Thankfully, such cases are rare. This is more a reflection of the relative infrequency of gun crime in this country, than a reflection of British citizens' inability to defend themselves.
While we are at it, I should say that the text kaffir qotes is a biassed, selective text which attempts to show that law-abiding British citizens need guns in order to defend themselves. The author of that selective text chooses not to mention all the American children who die, or who kill their siblings and friends when playing with parents' weapons. She does not mention the comparative rates of death and injury by shooting in the US compared to the UK. Here, a single death by shooting is so unusual it makes the prime-time national news. In the US, of course, such murders barely make the small print of the local newspaper. They are a commonplace.
I'm going to leave you with a quote from J. K. Rowling. She has never (so far as I can determine) discussed gun control in public, but when asked about the violence and deaths in her books, she gave the following response. I think it shows quite clearly where she stands:
People die, but do you care when they die? Do you absolutely have a sense of how evil it is to take another person's life? Yes, I think in my book you do. I think you do. I think you see that is a horrific thing. I have enormous respect for human life. I do not think that you would read either of the deaths in that book and think, yeah, well, he's gone, off we go. Not at all. I think it's very clear where my sympathies lie. And here we are dealing with someone, I'm dealing with a villain who does hold human life incredibly cheap. That's how it happens: one squeeze of the trigger. Gone. Forever. That's evil. It's a terrible, terrible thing but you're right, I know where I draw the line. Other people will draw the line in a different place and they will disagree with me.
Thank you and good night.