There is some question as to whether or not he had the bushmaster in the school. If that is the case, he did all of the killing with hand guns with normal sized clips.  So restricting the size of the magazine, would have made little difference.

Plus, I question whether an extended magazine would have had that large an effect even if he did have it. He is not going to be standing there, flat footed an firing off all 30 or whatever rounds. He is going to fire a few round, assess the environment, fire a few more rounds, perhaps move to another location. During each one of those "pauses" he would have a chance to replace a "normal" sized clip/magazine.

If he fired one round after another as fast as he could until the magazine was empty, his accuracy would decrease dramatically.

That may have been the case, but we're talking about measures that would IMPROVE the likelihood of survival,  because there is no one thing that will completely solve the problem.
As far as extended magazines, it may only take a few seconds (for a well-trained individual, which alot of school shooters are not), but it may be those few seconds that save some lives.

This is a little more concise, Solar.

"An armed society is a polite society. Manners are good when one may have to back up his acts with his life."
-Robert A. Heinlein

That may have been the case, but we're talking about measures that would IMPROVE the likelihood of survival,  because there is no one thing that will completely solve the problem.
As far as extended magazines, it may only take a few seconds (for a well-trained individual, which alot of school shooters are not), but it may be those few seconds that save some lives.

Problem is, like drugs and guns, regardless of the law, high capacity clips will always be available.
I can get any size magazine I want, you just have to be willing to pay a bit more for them.

It does sound simplistic, but new laws really do only affect the law abiding. Means nothing to those intending a massacre.

It isn't about the crazies - anybody with the sense that GOD gave a rock, realizes there isn't much we can do about them - except be prepared to shoot back when they show up. All this talk about new laws is ALL about getting weapons out of the hands of law abiding citizens.

Stepping back and asking a few questions.

 1. Do we have an increase in shootings in schools? ..................... I would say Yes.

I'm 75. I can't remember any school shooting 50 years ago. I went to a all boy College preparatory school in Chicago in 1954.  There were 4,500 boys enrolled. We did not have police stationed at the school. All the Chicago schools do now.
What Changed?

2. In Chicago where they have had as many as 900 homicides in one year, who is committing the crime?
Crime in Chicago - Wikipedia
http://en.wikipedia.org/wiki/Crime_in_Chicago
Homicides in Chicago 1990-2012

    1990: 851
    1991: 927
    1992: 943
    1993: 855
    1994: 931
    1995: 828
    1996: 796
    1997: 761
    1998: 704
    1999: 643
    2000: 633
    2001: 667
    2002: 656
    2003: 601
    2004: 453
    2005: 451
    2006: 471
    2007: 448
    2008: 513
    2009: 459
    2010: 436
    2011: 433
    2012: 491

   
The answer to the number two question is easy. In Chicago 90 % of the crime is committed in 10% of the geographic area in Chicago.
You can see a nicely colored chart by copying the Wikipedia URL above. 

I can go further on the homicides in Chicago.

Of the "Offenders" = 90% have prior felony arrest records

But there is a little surprise with the backgrounds of the Victims > about 70% - 80% of the Victims have prior felony arrest records

The other factor is drugs are involved in about 80% of crime.

The African American murder victimization rate was approximately 34 per 100,000; the Hispanic rate was 11 per 100,000, and the white rate 3 per 100,000.

Over 75% of victims and 88% of offenders had a prior arrest history.
11% of armed robbery victims were female,
50% of domestic victims were female, and
7% of gang-related victims were female.

31% of armed robbery victims were over 45 years old.
 29% of domestic-related murders were committed by women.

From 1991 to 2005, 19.2% of armed robbery murder victims were white, and only 4.3% of armed robbery murder offenders were white.

What that says is most crime is black on black and most of that is mostly in localized black communities and mostly committed by 17 - 25 year olds.

That's crime in general.

Our Media / Press usually ignores all that crime.

They love the Zimmerman / Martin, the Duke LaCrosse, the Columbine and the Newtown type.

The race baiters love it
The far left Libs love it
and Our Media / Press love it
 
Anything they can turn into a serial saga like the  OJ Simpson murder.

So we have two kinds of crime.
The run of the mill mostly black youth on black and the crime that invades society with sensation murder that can be exploited.

Are there any common characteristics between the two?
What are the distinct differences - particularly in the mass shootings?

Well in the Mass shootings - in every case

1. The Perp told other people of their intent.

2. The Perp or Perps were mentally unstable

3. The Mental instability was known by more than just the parent.
4. It was known by responsible people - people that could have interceded with just a little more authority.

Stopping Newtown type of crime.

Nancy Lanza had gone to court to institutionalize Adam. (Without success)

There needs to be a way to temporarily have some kind of authority intercede on an emergency basis.

What are the other society changes?
Drugs sex permeate the entertainment  media / industry

I'm sleepy I may reply to a reply to add more

The absolute number one, indisputable reason for increased murder of any kind, the destruction of the family by the left.
Removing God from the public venue, be it school or Govt building and Hollywoods need to promote an anti Christian view of how our country wants to live.

USAPATRIOT  I saved your picture for my archive.

I agree with Darth and Solar 

I don't know about the smarter people than you though.
[[[ Smarter people than I have said that they would rather their children see to people making love in a movie than have them see a movie where one person dismembers another with an axe.]]]

Overall, I think graphic sex is also almost as undesirable. It does nothing to elevate courtship and love in relationships.

There are it seems to me multiple different problems with graphic violence.

1. Don't you think there is probably a difference with the frequency of the exposure to graphic violence?
In the 40 - 50 the bad guy got shot and fell down.
Today you might see a throat cut and arterial blood spurting ("""in slow motion""") to heighten the shock. But you see it enough times it no longer shocks.
I don't (can't) watch graphic horror movies.
I had more than enough in the Military.
I am not entertained by seeing people brutalized or killed.
In fact that is a subject I need to explore in depth. (The media graphic violence)

My short response is - Violence does not turn normal people into serial killers or mass murderers. But there is always a bountiful supply of candidates that until they explode remain anonymous.
People that are that way are unstable and have probably been that way for a considerable length of time.

I strongly hesitate to say = >> we need to become more scientific and precise in determining who is a potential mass killer.
Just that thought is fraught with many unholy alliances that can be a invitation for those that have the skill and authority to examine and put anybody under their microscope that does not """neatly""" fit into their conceptual construct of of desirable political, social, emotional ideological characteristics. beliefs and values.

It's almost better to have the occasional mass killer than give the government another excuse or reason to develop means to further control the citizenry.

I make a distinct difference between Media & the Media / Press. They are two entirely different animals and in my opinion should be clearly identified when speaking of either.

The "Media" is much more of a political indoctrination machine than the Media / Press. Within the Media it is not just graphic violence -

It is the Media > and < the Media / Press that together set the "standard bar" for society. They steer society conduct and politics. The public has been mostly ignorant and unable to mount a coordinated effort to blunt or refute it. In fact they both have been engaged in a program of far left Liberal brainwashing / indoctrination for 50 years.
Political messages, thoughts, perspectives that are common today would have been stomped on in 1950 and called Communist, Leninist, Socialist or worse.

What is different today?

No Heroes (Figuratively) No good guy on a White Horse to fight for right and conquer the bad guy
No good honest respectable hero "role model" Today the bad guy is just about indistinguishable from the good guy.
When there is a difference our Media & Media / Press quickly burn the good guy at the stake if he's Christian or Conservative!

Who are or have been  the role models today?

Rappers, criminals, drug heads, alcoholics, crazy people, radicals, conspiracy theorists, terrorists,
Ispo facto  lindsey lohan, Charlie Sheen, Demi Moore, Kim Kardasian, Jesse Jackson, Al Sharpton, Louis Farakhan, Mumia Abu Jamal,

Our Media / Press and Media do not denigrate or disparage any of them. But take some Conservative or Christian and they will slice and dice them into fine hamburger.

What doesn't exist as a valued and admired trait and  is not  promoted on TV - real romance, courtship, respect, honesty, honor, integrity, Christianity, belief in God, family values, spousal commitment. etc:

In fact programs intentionally integrate into their plot / story line, the depiction of Christians, Conservatives, Republicans, right wing persons who are identified as the "Perp"  They are now representative of the vile child molester, the homophobes, the wife beater, the serial killer, the killer of Gays, the bomber, the terrorist and on and on. A good example of that  is "Law & Order - Special Victims Unit" - the program with Det Stabler and Benson

Today there is no respect for anything.
Rappers spent 30 years turning police authority into a pig sty. women into "HO's" and drugs into delicious candy. Yes, yes > "Kill the Pigs"

All of the above does nothing to elevate society.

Gun Control will do nothing to stop the crap.

One thing I predict is - a dramatic increase in Islamic terrorism - particularly in the US.

I have to stop - my dog is bugging me to go out.

I think if we had a law making it illegal for children to take loaded guns to school, we wouldn't have these kinds of shootings