Overthrowing a school = not cool. Gun laws are changing in the US. They will only go one way.
The UK evolved to outlaw guns progressively. The bill of rights meant that all protestants in England could be armed, initially this was a crossbow but later rifles and pistols as they were developed. This became law. As the colonization of new lands around the world occurred this law came with it. The US right to bear arms is the UK right to bear arms. Since then the law was changed in the UK to prevent the ownership of these weapons because of the crime they were causing. There were a lot of guns. The change to licensed guns happened. Further acts came into force to manage these guns and restrict them from access by children. Soon after WW2 automatic weapons were made illegal. Recently, in 1996 all pistols were made illegal after the Dunblane school massacre. Every single gun in the UK has to be licensed now and owning a gun is easily possible (not pistol or assault rifle) through a license. As a result the UK has the lowest rate of gun murders in the world. These changes were driven by public attitude.
I would estimate that if you were to plot the percentage of gun owners in the US and UK over time, the US would have tons more. As has been said, gun culture in ingrained into the way of life in some areas in America.
When the handgun ban here went through, most people probably didn't care or agreed that it was a good thing because they have no interest in guns and have probably never seen one. The US is completely different, in some places everyone owns a few guns and has done for decades. Threatening to take their birthright away over a few unrelated incidents is simply unacceptable to them.
The reason there is such a divide on this is because of the difference of attitudes and laws regarding guns across the different states. The key here is states. States decide the regulations on firearms except for fully automatic weapons and the like which require federal licensing. The feds shouldn't be the ones proposing a blanket ban on certain firearms when the states very so wildly in gun culture. If you don't like gun laws in your state, move to another one. That's the idea of having a /union/ of states, the republic of America is being eroded and this is a stepping stone towards complete federalisation of America, which a lot of people are opposed to. It's what the civil war was partly about.
I agree that you shouldn't just give out guns to everyone, but the new proposed ban is a death sentence to the firearms industry. If you were to completely remove guns from legal owners, you open up a huge gap for criminals, who will always be armed even if you ban weapons, to step in. The people lose out.
It's also worth mentioning that 13 'mass shootings' occurred in the United States last year and most of them weren't reported in wide media because it wasn't white school children getting shot. Incidents where a bystander ends the gunmans spree with a legal weapon are not reported because this doesn't support the anti-gun agenda being pushed by various groups.