The 2nd amendment says:
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
We need to remember that when the constitution was drafted, guns were not just for hunting or self-defense or target practice. They were the weapons of war, which had just freed our country from the tyranny of the British government.
The reason no one in their right minds wants any kind of ban on guns that prevents guns from being readily accessed and used is to prevent our current government from becoming tyrannical. They have to take away the guns -or just keep making them harder and harder to get- before they can make many inroads against our other civil rights.
But, once it's impossible for the average person to get guns, all the average people are hostage to whatever happens next -the loss of free speech & the free press, being subject to search and seizures (ergo losing any guns they've hidden), etc.
No one in the USA wants that. Or, at least, no one in the USA should want that.
I think if the gun control advocates want to make real inroads toward finding ways to keep guns out of the hands of those who should not have them, and lower the murder rate, they have to approach the issue with the reasons for the 2nd amendment's existence in mind.
Remember: the Constitution is not an ideal, or a best-case-scenario. It's the law.
In some ways, I'm jealous of those in the UK who see their government as a benevolent entity providing for the peoples and working with the overall health of the population in mind.
However, I'm quite American, and at the end of the day I do not -will never- trust our government to put the welfare of the citizens above the person desires of those in power. Nor do I have to go far to find examples of this happening already -from enacting laws forcing people to buy various forms of insurance to seizing assets from those merely suspected of a crime, many of us see the rights to bear arms as a necessity. If our government falls too far out of line with what most of us want, a revolution (or the mere ability to bring one) is the only thing that will protect our free states.