You don't think that maybe an attitude that the appropriate response to being shown "disrespect" is to kill the offending party played a more fundamental role that the availability of firearms? See, this sort of thing also occurs in the UK (albeit with less frequency), despite the lack of handguns, and pump-action and semi-automatic long guns, that might be diverted from the legal market.
One thing the U.S. and UK do have in common is an influx of Jamaican drug gangs from the late 1970s/early 1980s onwards. The "Yardies" (in the UK) and "posses" (in the US and Canada) were noted at the time for being extraordinarily willing (even for organized criminals) to use extreme violence with minimal provocation. These
mores appear to have caught on with black organizxed criminals of non-Jamaican descent. I'll admit I'm speculating here, but perhaps some of the discrepancy of scale between the U.S. and the UK in this regard can be explained by the fact that, as of 2000, 12.3% of the U.S. population was black, compared to 2% of the British population in 2001.
By contrast, according to the 2006 census, the Australian population contained around 9,000 people who were either born in, or claiming ancestry from, the Caribbean, of whom just 2,500 were of Jamaican background. Out of a population of 21 million or so, we're talking a few hundredths of a percent. One of the effects of not having a past of slavery or being the colonial power, I suppose, though perhaps the "White Australia" policy had a thing or two to do with it as well (since established immigrant populations tend to pave the way for more immigrants).
Historical evidence indicates that you can't just "get rid of the gun proliferation." Even in countries with stringent laws on private ownership like the UK or the Netherlands, organized crime can get hold of all the guns they want, with enough left over to sell (or rent) to any petty criminal who can stump up the cash. Their main suppliers are organized criminals in the Balkans and the former Soviet Union, where organized crime frequently has direct ties to elements of the government, such as the Russian FSB). Even in mainland China (where a private citizen can legally own a .177-cal air rifle at most, and that requires a permit), criminal gangs acquire firearms directly from the corrupt employees of the various arms manufacturing firms. The proliferation of firearms among the criminal element is driven by demand, not supply (I don't know how often I've pointed this out by now), and as long as there is a demand for weapons with which to kill competitors and people who "disrespect" you, some fucker will cater to that demand.
The long and short of what I'm getting at is that the homicide rate is determined to a far greater extent by having a cultural attitude among certain segments of the population that inclines one toward resorting to homicide as a response to both "business disputes" and affronts to one's personal honor, and that prevalence of firearms is secondary to that. It's notable that the homicide rates in mediaeval Europe were far higher than even American ones today, despite the relative (and prior to 1350, complete) lack of firearms. It's even more notable that European homicide rates started dropping from the 17th century onwards, well before the adoption of gun control laws, but following in the wake of the Enlightenment, which--among things--planted the seed of the idea that tolerating an insult was less of a stain on one's honor than willingly cutting short a human being's life.
Those of us who were born and raised into societies (or parts of societies) which take it as read that an offense to one's honor is insufficient reason to murder someone can be at a distinct disadvantage in trying to understand why a murder takes place. In her book
Nine Parts Of Desire: The Hidden World Of Islamic Women, journalist Geraldine Brooks (an Australian, as it happens) describes a court case in the UK of a Sudanese man who had stabbed his (also Sudanese) wife to death.
At issue in the court was whether the act was premeditated murder or, as the defense claimed, manslaughter that took place when the accused was temporarily out of his mind as the result of "reaction depression" brought on by the knowledge that his wife had had an affair, and that she had, on the morning of the stabbing, obtained a court order restraining him from taking their children out of Britain to live with his family in the Sudan.
As I listened to the facts of the case, I could interpret them in two ways. The Western way, as the jury was interpreting them, led to a description of something we all understood: a crime of passion in a spur-of-the-moment insane frenzy. The other way, the way I'd learned living among the women of Islam, described something very different: a cleansing of family honor, a premeditated killing that would, under British law, draw a sentence of life imprisonment.
From where they sat in their jury box, the men and women of the jury couldn't see Omar as he stood each morning beside his police guard, waiting to be escorted into the court. But from the elevation of the public gallery I could see him, and so could his brothers. Each morning he looked up at them and raised a clenched fist in a defiant victory salute.
But as I've pointed out before, what Brooks describes as "the Western way" of understanding a homicide is based on a myth. Spousal killings do not occur in a "spur-of-the-moment insane frenzy"; they are just as deliberate and premeditated as Omar's, with the only distinction being that the Western spouse-killer is spurred not by a need to protect/restore the honor of his family or clan, but his own.
In a very real sense, the killing of persons who supposedly show "disrespect" is also an "honor killing." And restricting the means to commit those killings will have little to no effect as long as the cultural imperative exists to commit the killings. What Judge Walker failed to acknowledge was that the use of firearms follows from the desire to kill, not the other way round.