"How can anyone support US gun laws? The colossal US homicide figures and the number of firearms deaths are a direct result of these gun laws."
Less law, more culture. Switzerland has an enormously high gun/capita rating, but very low crime. And the highest rates of murder in the US are in areas like Chicago and LA, which have the tightest gun laws in the US - total bans on handguns, etc in some counties.
The other problem with talking about "American Gun Laws" is there are no such things. There are a few federal laws, and then state/county laws, and this is the right thing. Grouping New Mexico, California and New York in one breath as "America" is as broad as grouping the UK, Spain and Romania as "the same" because we're all Europe. If you live in a leafy suburb of the Hampshires, you're unlikely to need a gun for self defence. If you're a rancher in New Mexico near the border with DEA and drug runners fighting running gun battles across your ranch, actually it's a genuinely hazardous place to live.
Interestingly, if you remove the three worst cities from the stats (LA, Chicago and I think Detroit), the rest of the US actually comes down to European levels of firearms deaths. And that's not an unfair thing to do - it still includes big urban areas like NYC, Seattle, Houston and SF. What it indicates is those three have very specific problems, and actually, in the rest of the US firearm laws don't really pose a huge problem. Federal laws would be overkill to deal with the individual issues of specific cities and for the same reason probably wouldn't actually do a very good job.
Also, there's a limit to how far the feds can actually exert jurisdiction. For instance, if a gun is manufactured, sold and owned within Texas, then local law could overrule a draconian Federal law and say "What goes in Texas stays in Texas, none of your business."
I'm not by any means suggesting there isn't a lot of room for improvement, but even if the Federal government decided to take dramatic action, individual states could cripple the legislation with respect to firearms manufactured and sold in-state.
The other thing worth bearing in mind is a tad over 50% of firearm deaths are suicides. I heard someone on the radio churning out the 30k firearms deaths/yr figure again today.
Well, 15k of those are suicides. Even if you somehow banned all guns across America and made it stick at a state level, you're not going to get rid of the suicides. That needs for America to sort out their abysmal public mental health provision. Focussing on the gun is treating the symptom, not the root problem. Of the other 15k, a fair number will be legitimate Police or self-defence shootings, then "accidents" (negligent handling), and then murders and homicides.
Of the latter group, it would be interesting to split out murders from legal and illegal guns. Legislation doesn't touch illegal guns - they're already black market. The only way to address them is enforcement. Making them more illegal doesn't work!
In the UK in 1997 gun crime was on the up. Less than 1% of firearms crimes were committed with firearms that had ever been registered. Dunblane was an horrific aberration, but even following the ban, gun crime just carried on rising because the ban on handguns didn't touch 99% of firearms crime! It didn't peak out until 2003-2005 when Operations Trafalgar and Trident started to hit home taking smuggled guns out of circulation.
Point is, the argument is now hopelessly polarised.
People calling "Ban Guns" are as bad as people calling "Moar Guns".
Banning all guns wouldn't address either suicides or organised crime, and they make up the vast and overwhelming majority of firearm deaths. By all means go after the shootings with legally held guns, but you're already onto a diminishing return as it's a relatively small part of the overall picture.
That doesn't mean do nothing, but I'm yet to see anyone make an attempt to come up with sensible suggestions that systematically address the root problems.