If the US adopted the gun laws of, say, Australia or the UK, its murder rate would gradually (over a decade or two) drop to (conservatively) 1/3 of what it is now. Everyone knows this to be true: US rates of burglary, assault, car theft etc. are mostly comparable to the rest of the developed world - so the idea that the US is just more evil or degenerated on average (or whatever it might be) simply doesn't stack up - it's murder that's the big anomaly. And while Aurora-like events can and do happen everywhere, there's every reason to believe that, were the US to adopt OECD mean gun laws, the US would gradually regress to the OECD mean for rampage-killing too.
But supposing the US can't/won't ever fully see reason about its gun laws, then still restrictions on semi-automatic weapons, background checks, maybe restrictions on numbers of weapons, types and amount of ammunition an individual can own - that sort of thing - would be a positive step, would help block the currently royal road the US paves from being a disgruntled crazy person to being a hugely destructive rampage-killer.
Depressingly, however, the NRA and its followers resist even such modest steps in large part on slippery slope grounds which we spoof as follows: 'If we allow reason about guns to gain any sort of foothold then before you know it we'll feel the full force of the better reason and be turned into Australia/Canada/Europe.'
The US likes to think of itself as a shining city on a hill. No chance of that as things stand: a dark, cautionary tale about how not to fashion a society is more like it. One can love a lot of things about the US but also despair of its special insanities. The current murder rate and the embarrassment and moral damage it represents for the US isn't going to stop until the US wises up.
Further Clarifications
1. In discussions with Americans about their gun polices two countervailing considerations in favor of extremely light or even no control of the gun supply often emerge. First, there's the idea that a heavily armed civilian population is extra insurance should the US ever be invaded, etc.. Put slightly differently, Americans, like the idea that even if the official military failed civilian militias could form and easily turn the US into a kind of unoccupiable, super-Afgahnistan. Second, there's the idea that Americans might have to eventually take up arms against their own government or one another, in deed that it might be periodically desirable and even necessary to refresh the tree of democracy with the blood of tyrants as Jefferson once memorably put it. From the perspective of this later point, while citizens of Australia or Canada etc. might be perfectly happy with their lots but they haven't built the same level of security against internal threats of tyranny into their democracy that Americans have. The American tradeoff is, say, 5000 extra deaths per year to insure against a long-shot nightmare
2. The basic point to be made against both these ideas is just how bad these tradeoffs are. We're talking (very very conservatively estimated) 5K extra deaths a year = 500K per century to insure against (i) the failure of a military that costs as much as the next 15 largest militaries in the world combined, and (ii) the complete, de-constituting, breakdown of the US form of government, i.e., a civil war-level crisis. The US Civil war saw 500-700K deaths (more than the deaths from all of the US's external wars combined).
3. (i) Strikes me as bizarrely fanciful overkill. So the big US tradeoff comes down to insuring against the ultimate internal catastrophe by amortizing roughly that level of additional death over a century! But that's lousy insurance. Expectation of a civil war equivalent (CWE) every century is not a mark of a successful or even functional liberal democracy. I'd say that somewhere between .1 and .2 CWEs is a better and more realistic target. The main argument in favor of liberal democracy after all is that it's self-correcting, that it allow conflicts to be resolved from within a political process, so that all groups in society can influence policy particularly in areas that are important to them. The American trade-off therefore looks like a very half-hearted embrace of the American instance of liberal democracy. Anticipating and paying for 1 CWE per century isn't a deal that anyone else accepts, and it's undermining of liberal democracy's claim to being the best political system that any country takes that deal.
4. Note too that it's especially exasperating that the political group that most virulently supports very 'expensive' firearms insurance against incredible longshot possibilities (which are in any case amenable to other, 'cheaper' measures, e.g., just don't slumber when demagogues start to gather popular support) has no time whatsoever for climate change issues: the threats posed by ever increasing CO2 levels pushing global temperatures ever higher are real/highly probable/firmly predicted at this point not longshots, and there are no known, effective acceptable, affordable alternatives (i.e., to reducing net CO2 emissions fast) that will avert or even much blunt the expected catastrophe.
