Mr McDowell,
Due to the focus of your book and of this forum, I believe we are fixating entirely too much on "firearms."
It should not surprise us that firearms are used in the commission of violent crimes. They represent the pinnacle of personal weaponry in 2007. Police have firearms because they are efficacious. Criminals desire them for the same reasons. This is a simple truth.
However, while drastic measures controlling firearms would most likely reduce the frequency of firearms used in the commission of violent crimes [assuming these measures could be effective given the 'after the fact' nature of law enforcement and the large number of firearms in circulation], I tend to doubt that the overall violent crime rate would drop as well.
As has been previously pointed out, cities with draconian gun control laws tend to have significantly higher crime rates. This is merely a correlation, but one I believe is significant.
(1) It shows that gun control does not in itself lead to a reduction in violent crime. Crime by definition is the violation of law. Will addition laws prevent crime? If they do it will be through psychological deterrence. (Incidentally death penalty debates and psych studies present some fascinating info on this area that I cannot due justice to in this post.) Criminals do not want to be caught or countered. Hence while they might not have any scruples in committing acts of violence, it is reasonable to assume that they try to reduce any ancillary 'risk factors.' The legal penalties for the possession and/or unlawful use of specific weapons and other tools may shape the means, but have not addressed the cause, nor prevented the end. For example, carrying a crowbar will get you charged with burglary tools. Wearing body armor in many areas will get you charged with a possession/use in commission of a felony. Therefore, a criminal must decide whether the value of body armor or a crowbar is worth the additional legal penalty. Conceivably, if gun control laws carry most severe penalties than laws against the use/possession of other weapons, we might see a reduction in the use of firearms in crimes. (As an aside, weapon control laws in CA actually encourage the illegal firearms. Carrying saps, blackjacks, and fixed blade knives [arguably the next weapons down from handguns in terms of efficiency and convenience] is a felony, while illegally carrying a handgun owned legally by one over 21 is a misdemeanor. From a cost/benefit analysis, it seems the handgun is a clear choice.) However, while other weapons remain readily available, it is doubtful whether a significant reduction in overall violent crime will be seen. Violent crimes are committed with kitchen knives, pocketknives, baseball bats, axes, tire irons, and countless other weapons. Prisons are a perfect example of this. It is my belief that severe gun control restrictions will only alter the weapons of choice, not the intent to commit violent crimes. Bear in mind though, that these draconian restrictions apply equally or more so to the law abiding. Handguns are most efficient personal weapon for everyday carrying ever devised. This applies to whoever uses them, criminals, police, or normal people. For women, the disabled, and the physically challenged, firearms represent the most effective means of self defense. Tasers and pepper spray are the only real alternatives for a majority of these people, and are significantly more limited and less effective than firearms. If severe gun control shifts the focus toward less efficient weapons, will it really have done the disadvantaged a favor? Criminals are overwhelmingly young to middle age males, where aggressiveness and physical abilities have peaked. They are significantly better equipped to use to less-efficient weapons: knives, blunt instruments, hand-to-hand. Firearms are used because they represent the top of the food chain. If you were to somehow lop off the top, violence continues, just with different instruments. Prisons are a classic example. In a severely regulated environment where all weapons are prohibited, violent inmates create and use improvised weapons.
(2) Prisons, Washington D.C., and other areas where there is strict gun control and higher violent crime rates strongly suggest something: that sociological factors other than firearms/weapon availability are responsible for most of the violence in those areas. Prisons are the definitive example of weapon prohibitions serving as an inconvenience, not a deterrence, to those with criminal inclinations. Too often, I think, gun rights advocates point to the 'gun control = more crime; more guns = less crime' phenomenon. While the availability of firearms certainly plays into the hypothetical criminal's cost/benefit analysis of a mugging (the more chance a victim is armed, the more risky it is), I believe the dominant factors are sociological. For x reasons, there are high crime rates. My personal hypothesis takes this one step further. The members of the general public in favor of gun control usually see it as a reactionary measure. An unacceptable number of crimes have been committed. Many committed with firearms (due, as I pointed out above, to their supremacy as personal weapons). Then someone tells them that they can reduce violent crime by stricter gun control. They see it thus: less guns = less crime. Unfortunately, correlations within the United States do not support this theory, most damningly so when other sociological factors are accounted for. Due to the common mis-perception, however, I believe high-crime areas tend to develop stricter gun control laws. In conclusion I suggest the following: (a) While high levels of firearm carrying does indeed deter interpersonal crime, (b) the reaction to already unacceptable levels of violence is often to pass gun control laws which are ineffective, (c) hence the correlations between firearms ownership levels, gun control, and crime rates. Comparing the United States to Britain is fallacious and disingenuous from a sociological point of view. One compares apples to apples, not oranges. Unfortunately, we sees very few comparisons within the U.S. advanced by proponents of gun control because the statistics and correlations do not support their assertions.
You mentioned a few other points that I wish to address as well. As has been pointed out, longarms (any firearm other than a handgun) are responsible for a tiny fraction of firearm related crimes, and so-called assault weapons are responsible for only a fraction of that. This is because of the convenience of handguns in everyday carry. Consequently, when I try in good faith to understand why gun control advocates insist on fixating on semi (as in not automatic, despite the common mis-perception) automatic rifles and long-range target rifles as targets for regulation, I am stumped. Yes, .50 caliber rifles are more powerful in the sense that there is more kinetic energy. No, one cannot easily make 1600 meter shot on a moving target. The limitations and liabilities, as virtually always, lie in the user. No, assault weapons are not easier in any meaningful way to use effectively. In fact, the less powerful a firearm is, the easier it is to shoot. Less recoil, more controllable. Yet .22LR rifles always seem to be the last thing to be banned.
All the arguments I have been presenting so far assume severe, draconian gun control laws. Registration and licensing, as you propose, is simply not effective at reducing crime. At best, a registered gun is traceable to its original owner, ex post facto. Registration has not prevented any crime from being committed. Straw purchases are already illegal. Handguns are already registered in many states, and licensed in several. Please elucidate how you feel registration and licensing will reduce violent crimes. Gun owners are generally hostile to such schemes because they have been historically abused and used to implement more gun control despite all assurances to the contrary.
I don't think there is an easy solution to the problem of violent crime. While your concern is laudable, I feel you are fixating on the instruments of violence, not the causes or solutions.
I have noticed you asking many questions, receiving many fine and several poorly-considered ones, and generally not addressing any of them. It is the nature of intelligent discourse to answer as well as to ask...