American Shootings continue

Having just returned from the USA I have had a number of conversations with people about the state of gun laws and access to guns in the USA and the responses are quite surpising.  50% for guns and 50% against.  The against lobby have all of the usual answers about needing more control and that would seem an obvious soultion but the for campaign have some intresting arguments which I would like to air here based on my conversations.

The 2nd Ammendment of the Constitution is a favourite with the right to carry arms.  A number of the people we met do just that.  The fact that the Constitution was written in the 1700's seems to suggest that its about time it was rewritten with the 21st Century in mind.  In those days you took your life in your hands every day with bandits all over the place.  Some of the present day population would state that nothing has changed but I beg to differ.  Pointing out that the British "Constitution" (if you can call it that) has evolved over time as judges make judgments based on present day situations and not those that took place over 300 years ago.  The American Constitution is a rod that is breaking the back of one of the most powerful nations in the world. Get rid of it and start to re-evaluate your priorities.
The other argument that comes up is the fact that Mental Health is what is responsible for these killings and that Mental Health patients are not being treated well and so more killings occur.  I agree that Western Nations need to do more for Mental Health patients but how is it that other western nations don't have this shooting problem even though they have Mental Health patients?  The reason is that they can't get hold of the weapons in the first place.  Access to weapons in the USA is completly open with few serious checks.  They argue that Chicago has the strongest gun laws in the USA yet there are more killings here than many other cities.  The people who argue this seem to forget that guns dont stop at the city boundaries and in fact most of the guns used in killings in Chicago have been brought in from other parts of the USA.  It like imagining that disease stops at our borders.  Viruses don't recognise borders either.
And another reason for having guns available appears to be as a deterent to robbery.  Having a gun in your home will act as a deterent? In that case I suppose robbery must be at its lowest in the USA compared to any other Western country.  Of course this is not the case.  So I'm afraid that is no deterent and people continue to get robbed and probably shot at the same time as burglars are more likley to be armed since the owner of the house may be armed as well.  Criminals see themselves as invincible so have no fear about carrying weapons.
When householders shoot people,even in the back, as they run away the "instruction" is to drag the person back onto your land so you cant be prosecuted.  What a ridiculous situation.  Everything a person does to protect themelves needs to be proportional.  If you life is in danger then the reponse should be different than if a person is running down the road with your TV.
And so the arguments go on.  And so do the killings.