The reason us Brits always have a go at America about it's gun laws is that we actually know better. We learned from experience. Hungerford, Dumblaine, when these things happened we clamped down on guns and it bloody well works.
The second amendment was created at a time where people would be lucky to fire a single round from and inaccurate musket. I don't think the founding fathers really had any clue that some day you could walk into a fucking supermarket and buy guns. It's pure insanity to believe that a set of rules shouldn't be changed over time if circumstances change. It's the difference between dogmatic obedience to a religion and people changing things in a religion to suit the modern world.
The wording of the second amendment is also woolly as fuck. "The right to bare arms." Okay then how many arms? Can I have one gun or as many as I like? Also what type of arms? Are we talking just handguns or rifles? Where does it end? RPG's? Tanks?. Obviously the answer to this is "We make laws to state what you can and cannot have." Great, now tighten up those laws when you see people doing things they shouldn't do. Tighten the laws saying who can own a gun. Tighten the laws for background checks, Tighten the laws for who can sell a gun. Tighten the laws for the sale of ammunition. Do these things and maybe, just maybe, you will have less mass shootings.
It's common sense. Sadly, just like our own politicians (only to a lesser degree), common sense seems to be lacking in American politics.