I think that the situation in the USA is far too complex for any of us, in another country, to understand.
For a start though, let's be aware that the laws do depend on the individual states, basically the metropolitan areas tend to have tougher laws than the more rural areas, i.e. it isn't possible to just go and buy any gun with no questions asked, in most places.
I've worked in The States, and my impression was that the vast majority of people in cities don't have guns, don't want them and disassociate themselves from the people who amass huge arsenals of guns and who constantly witter on about their right to bear arms (which was intended to be a collective, rather than an individual right).
The extremist behaviour (i.e. murderous attacks) seem to be more or less restricted to gun nuts, who have these vast collections of automatic weapons, and who also stockpile unbelievable quantities of ammunition (possibly based on the belief that President Obahma was planning to restrict their future buying).
But even some 'normal' people can be well over the top, by our standards. I remember a long conversation with a guy who lives in Boston, Mass - a medical doctor so not stupid - who told me that he has at least 2 9mm semis hidden in every single room in his house, in condition zero, just in case of attack, and despite having young kids...
And many Americans seem to be obsessed by excessive power - look on the forums, there are loads of questions about which type of shotgun ammo is best for home defence, with nearly everyone opting for massvely powerful magnum cartridges loaded with the biggest possible pellets. There was one tragic case that I remember, the householder shot a burglar at close range, the shot went through him, through the wall behind him and killed the 17 year old daughter who was behind the wall - it would be funny if it wasn't tragic, because even the low relatively low powered clay cartridges that I use will kill, without question, at 30m, and there aren't many homes that have rooms larger than that...
As for the types of guns that people are allowed to own, I see no legitimate use for fully automatic, semi automatic or for action mods that convert semis to full auto, these weapons are designed for military use and have limited application for law enforcement agencies, but have no legitimate application for private owners.. Nor do I see any legitimate private use for multiple shot semi auto handguns such as the Glock range, which being made largely from plastic are harder to detect with security equipment.
If people are into target shooting, then single shot Martini action, or bolt action, is all that's needed (rapid rates of fire heat up the barrel and destroy accuracy) and if people are into hunting animals, then bolt action is perfect, and safe - no need whatever for anything that can be fired faster.
I believe that we've got the balance about right here in the UK. We have the freedom to own guns provided that we are of good character, don't drink excessively and in good health. Many people own shotguns for pest control or for shooting sports, and crime with these legally held firearms is virtually non-existent. And a lot of us have rifles too, but if we want to buy a rifle then we need to demonstrate a good reason for having it, and there are restrictions on the amount and type of ammo that we can buy. .22 Semi auto rifles are used for some shooting sports, personally I don't like them but I do accept that some people do have a good reason for having them - I'll stick with my bolt action rifles, the ones that I have can hold between 4 and 10 rounds, and that's more than enough for legitimate use, IMO.
As for handguns, these are even more tightly controlled and require a S.5 certificate. Those of us who have them for humane despatch, can only load 2 rounds, which is 1 more than should be needed by a competent shooter putting an animal out of its misery. Black powder (gunpowder) pistols are available on S.1 certificates, but these are not really serious weapons, and the long pistols that are also available for target shooting, again on S.1, aren't serious weapons either.
Also, although the police firearms licencing departments have responsibility for the issue and revocation of certificates, we in the shooting community also regulate ourselves, and effectively control people whose behaviour changes and gives cause for concern.
Coming back to crime and spree shootings, there have been 3 within my memory, Ryan in Hungerford, Hamilton in Dunblane and Bird in Whitehaven. That's 3 too many of course, but in each case those of us who are into shooting know that the police issued firearms certificates to people who weren't fit to have them, and murders resulted from their failure to do their job properly.