This question has been bandied about by people who don't know guns, as some sort of rhetorical trump.  The answer is somewhat complicated for people not versed in the subject, but I'm going to have a whack at it.

The AR15 is a development of an earlier rifle in a larger caliber—the .308 caliber AR10.  The "AR" is from Armalite, the designing company, which at the time (early 1950s) was a division of Fairchild Aircraft.  Some of the most sophisticated alloys and machining techniques were used in its development.

Keep that timeline in mind—1950s.  AR15s have been in military use since 1959, and on the civilian market since 1963—longer than most of you have been alive.  If you're just now becoming aware of them, you're 50 years, half a century, behind the curve.  There have been improvements in this time, but it's been around for two generations.  This might even be your grandfather's gun.  The 30 round magazine, by the way, has been STANDARD CAPACITY for 40 years.  You don't get to redefine it as "high capacity" just because you've recently become aware of it.

The AR15 receiver is made of light, very strong aluminum alloys, to quite tight tolerances.  The barrel and operating parts are various steel alloys, chosen for specific characteristics.  The gun weighs 5-9 lbs depending on configuration.  This is quite light, at the bottom end for rifles, which makes it easier to handle for smaller people.  It's a fact that without the AR15, and its military analog the M16 (which fires in full auto or burst, which civilian AR15s are not capable of), there would be a lot less women in the armed forces or shooting sports.  Not only are earlier self-loading rifles heavier, they usually have heavier springs and operating masses, beyond the capability of many women and smaller men, and youths, to operate.

Also, the AR15 operates by what is called "direct gas impingement."  Instead of using barrel gas pressure to shove a piston to work the action, the gas directly hits the bolt carrier—the cycling part of the action.  There are pluses and minuses to this, but the big plus is a much lighter operating mass.  That means a lot less recoil, which makes shooting easier, and more accurate, for everyone, and makes it usable by some small people for whom a bigger rifle would cause bruising and injury.

It generally comes in 5.56mm, or .223 Remington, developed from what was considered a "varmint" round in the 1950s. Again, there are pluses and minuses.  One plus is that a lighter cartridge means even LESS recoil.  So again, there's an advantage for smaller people.  It's still an advantage to larger people, because recoil itself doesn't offer ANY advantage.  It's a side effect of shooting.  The less side effect, the better.  Also, a rifle is more powerful than a handgun.  The recent case of a lady firing 5 shots from her revolver http://www.cbsnews.com/8301-504083_162-57562397-504083/georgia-mother-hides-children-shoots-intruder-5-times-during-home-invasion-police-say/ without reliably stopping the attacker is an indication that handguns have limitations.

I mentioned "5-9 lbs depending on configuration."  The AR15 is a brilliant design that can be changed in caliber, barrel length and even stock type in a few moments, literally a matter of seconds for most changes in barrel or caliber, by swapping out an entire assembly held in place with two pins.  You can shoot .22 for practice, .223 for varmints, or .458 SOCOM in a carbine length for home invaders.  You can attach a heavier barreled assembly for long range target shooting or sniping.

And the adjustable stock, that 'evil feature' that makes it an 'assault weapon' to some people, means it can be adjusted to fit shooters of different statures or wearing various clothing –parkas vs T-shirts.

Detachable magazines do enable faster reloading, which is a good thing.  Fumbling with a gun while someone is trying to kill you is a bad thing.  Also, a detachable magazine makes it easier to UNLOAD a weapon, which also increases safety.

In addition, the military variant, the M16, has been in general use for almost 50 years.  Most veterans handled one at some point in their service, so an ergonomically similar rifle, even if castrated of its real military features, is familiar and easy for them to use, and to teach others to use safely.

So, it's a light, versatile, reliable, accurate, easy and safe to use weapon that is excellent for home defense, pest control, recreational shooting and making a political point against invaders and tyrants.  Every home should have a few.

As far as the AK47, it has some advantages over the AR15, some disadvantages, and generally costs ½ to 2/3 as much, so it's better for people on a budget.

Now, let's address some of the snide comments people are going to want to post.

Its political opponents like to bleat, "Guns are only good for killing," as if they've discovered some profound revelation, are standing on some moral peak, or have played some kind of trump.

Well, no, that is not true.  However, as far as killing, or at least stopping people, it is pretty good, and quite accurate.  They also seem to think that killing is a bad thing.  It's not.  Murder is a bad thing.  Killing should generally be avoided, but thousands of years of Common Law, and most state laws, do not prohibit the killing of an attacker, if your own life is threatened.  And unless you're Chuck Norris, an AR15 is a much better tool for this than your fists or a kitchen knife.

There's also the possibility of local or national insurrection or despotism.  While the US has avoided this so far, it is not an impossibility.  It has happened in dozens of prosperous, liberal nations over the last century.  If you deny this fact, or the possibility, please stop reading now and go back to your reality shows.

Don't take my word for it, though.  Let's see what the Supreme Court has to say:

There are many reasons why the militia was thought to
be “necessary to the security of a free state.” See 3 Story
§1890. First, of course, it is useful in repelling invasions
and suppressing insurrections. Second, it renders large
standing armies unnecessary—an argument that Alexander
Hamilton made in favor of federal control over the
militia. The Federalist No. 29, pp. 226, 227 (B. Wright ed.
1961) (A. Hamilton). Third, when the able-bodied men of
a nation are trained in arms and organized, they are better
able to resist tyranny.
Cite as: 554 U. S. ____ ( 2008 )

~~~

The most significant of these commentators was Joseph
Story. Contrary to the Court’s assertions, however, Story
actually supports the view that the Amendment was
designed to protect the right of each of the States to maintain
a well-regulated militia. When Story used the term
“palladium” in discussions of the Second Amendment, he
merely echoed the concerns that animated the Framers of
the Amendment and led to its adoption. An excerpt from
his 1833 Commentaries on the Constitution of the United
States—the same passage cited by the Court in Miller34—
merits reproducing at some length:

“The importance of [the Second Amendment] will
scarcely be doubted by any persons who have duly reflected
upon the subject. The militia is the natural defence
of a free country against sudden foreign invasions,
domestic insurrections, and domestic usurpations of
power by rulers.

...."The right of the citizens
to keep and bear arms has justly been considered
as the palladium of the liberties of a republic, since it
offers a strong moral check against the usurpation
and arbitrary power of rulers, and will generally, even
if these are successful in the first instance, enable the
people to resist and triumph over them."

~~~

3. Relationship between Prefatory Clause and
Operative Clause
We reach the question, then: Does the preface fit with
an operative clause that creates an individual right to
keep and bear arms? It fits perfectly, once one knows the
history that the founding generation knew and that we
have described above. That history showed that the way
tyrants had eliminated a militia consisting of all the able bodied
men was not by banning the militia but simply by
taking away the people’s arms, enabling a select militia or
standing army to suppress political opponents.
This is
what had occurred in England that prompted codification
of the right to have arms in the English Bill of Rights.

~~~

Story’s Commentaries
also cite as support Tucker and Rawle, both of
whom clearly viewed the right as unconnected to militia
service. See 3 Story §1890, n. 2; §1891, n. 3. In addition,
in a shorter 1840 work Story wrote: “One of the ordinary
modes, by which tyrants accomplish their purposes without
resistance, is, by disarming the people, and making it
an offence to keep arms, and by substituting a regular
army in the stead of a resort to the militia.” A Familiar
Exposition of the Constitution of the United States §450
(reprinted in 1986).

All from District of Columbia vs Heller, 2008.

There.  Several references to being able to fight a tyrannical government, all from four years ago, from the highest court in the land.  DC lost, by the way.

So, yes, the AR15 is made to kill people, and there are some people who need killing, so says common law, codified law, and the Supreme @#$ing Court.  Therefore, if you say, "The only purpose of a gun is to kill people," you're not entirely correct, but you are in fact making a statement that supports gun ownership. Thanks.  We're glad you've figured it out.  One of the main purposes of guns is to kill people who need killing.

"When all you have is a hammer, all your problems look like nails."

No. However, when the problem IS a nail, beating it with a screwdriver accomplishes nothing, and beating it with your fists only causes injury to yourself.  One well-placed hammer blow makes the problem go away.  Thanks for playing.

Just to reinforce this, here's the money quote from Heller:

http://www.scotusblog.com/wp-content/uploads/2008/06/07-290.pdf

"Some have made the argument, bordering on the frivolous, that only those arms in existence in the 18th century are protected by the Second Amendment. We do not interpret constitutional rights that way. Just as the First Amendment protects modern forms of communications, e.g., Reno v. American Civil Liberties Union, 521 U. S. 844, 849 (1997), and the Fourth Amendment applies to modern forms of search, e.g., Kyllo v. United States, 533 U. S. 27, 35–36 (2001), the Second Amendment extends, prima facie, to all instruments that constitute bearable arms, even those that were not in existence at the time of the founding."."

~~~

In America we have a constitutional right to own modern firearms for the purpose of killing people who need killing to defend ourselves, our communities and our nation.  If you don't like it, there is no law stopping you from leaving.  In fact, as an immigrant myself, I'd encourage you to find a nation better suited to your philosophy, as I did, and move there, as I have done.  In exchange, I have friends and relatives overseas who'd be happy to swap with you.

And my daughter thinks you're a sissy:

©2013 by Michael Z. Williamson www.MichaelZWilliamson.com 
Permission to share granted for non profit purposes as long as this notice is included.

I keep hearing people say they want to regulate guns the way we regulate cars.  They don't really mean that, of course.  What they mean is they want to make it acceptable to find more ways to intrude on the right to keep and bear arms.

I propose instead, we regulate cars the way we regulate guns.  Let's start:

To buy or operate a standard car, one will have to be 18 years old.  Under that age, adult supervision will be mandatory.  This means the adult must be in the vehicle with the underage driver.

To buy a sports car, you will have to be 21.  A "Sports car" will be defined as any combination of any two of the following: 2 doors instead of 4, spoked rims not requiring hubcaps, aerodynamic effects such as spoilers or air dams, a wheelbase under 100 inches, a manual transmission, a curb weight under 3000 lbs, fiberglass or other non-metal construction, or painted logos. 

For every purchase, you will have to fill out a questionnaire confirming you're a US citizen, do not use drugs or abuse alcohol, have never had a conviction for alcohol related incidents or reckless driving.  Lying on this form will be punishable by 10 years in prison and/or a $10,000 fine.

New cars will only be purchased from Federal Automobile Licensees who must provide fingerprints, proof of character, secure storage for all vehicles, and who must call the Federal Bureau of Motor Vehicles to verify your information before purchase.  They may approve or decline or delay the sale.  If they decline, you may appeal the decision in writing to a review board.  If they delay, it becomes an approval automatically after 10 days. However, the dealer may decline to complete such a sale in case of later problems.  

Additionally, the purchase of more than two cars in a given year will require signing an understanding that buying cars in order to resell them without a license is a crime.  There is an 11% federal excise tax on all new vehicles, plus any state or local tax.

Federal Automobile Licensees must agree to submit to 24/7/365, unannounced, unscheduled searches of their entire homes, businesses and any relates properties and personal effects to be named later.

Then you will be eligible to take your drivers' license test to determine your eligibility to operate on the street.  Rules will vary by state, with some states requiring proof of need to own a vehicle for business purposes, and up to 40 hours of professional education.  Also, not all states will accept all licenses.  You will need to keep track of this information. Additionally, speed limits will not be posted.  It is your responsibility to research the driving laws in each area you wish to travel through.  Some communities may not allow out of state vehicles, sports cars, or even any vehicles at all.  Violation of these laws will result in confiscation and destruction of your vehicle by crushing.

To have a turbocharger, supercharger (External Engine Compression Devices) or a muffler will require an application to the Federal Bureau of Motor Vehicles.  A $2000 tax stamp will be required for these High Performance Vehicles.  Your request must also be signed by the local chief law enforcement officer, and you must provide fingerprints.  If approved in 10-16 weeks, you will be responsible for keeping your High Performance Vehicle in secure storage, and request permission in writing to take it out of state.  You will need to carry this documentation with you.  There are 13 states that do not allow possession of High Performance Vehicles.  Be sure you are aware of those laws before planning your trips. (But really, what do you need such a vehicle for anyway? Who really needs to drive that fast? You must willingly accept and adhere to the socially accepted idea that you are inherently evil for merely possessing such a fast, high powered automobile.)

Additionally, superchargers and turbochargers must be manufactured before June 1, 1986. They may be sold and refitted by a FAL who also has a Special Occupational Tax license authorizing him to work on these.  New superchargers, however, are a violation of federal law, except for use by the police or military, or specific government contractors. Expect to pay $15-$30,000 each for these items.  Mufflers will only cost from $250-$1000, plus the $2000 stamp.  However, once the muffler is damaged, it must be disposed of by cutting it into three pieces. Failure to do this may result in your family going through the next decade only knowing you in a prison jumpsuit and all your bank accounts seized and never replenished.

Imported sports cars will be prohibited. You may purchase other items from foreign manufacturers, but your automobile is in a special class of prohibition due to its inherently evil and sinister nature. The frames may be imported, cut into three pieces, and reassembled with US made engines and suspensions, as long as 60% of the parts are American.  Shortly, though, the Transmission Loophole will be closed.  The purpose of allowing imports is for spare parts, not to build more destructive "race vehicles.”  Transmissions will have to be US made.

Repairs may only be conducted by a licensed FAL, who will send a truck to retrieve your vehicle.  It must be a flatbed type truck, winch/dolly trucks are not allowed, under 10/$10,000 penalty.  You may work on your own vehicle, but any repair that exceeds emission or performance standards will be subject to federal criminal charges. And violation of this reasonable regulation could result in not only your imprisonment and the confiscation of your assets but imprisonment of any employee or family member who was insane enough to repair your “race car” for you.

Be aware that an existing HPV may have multiple HP Features.  A new HPV will require a license for each feature you wish to add to it—one each for muffler or external engine compression device. And you must request and receive, in writing, permission from the federal, state and local governing authorities prior to making such modifications.

Converting a standard car to a sports car will require payment of a $2000 tax, even if no HP features are added.  However, if an FAL/SOT does the conversion on a new frame before the vehicle leaves their premises, it will only be a $50 tax.   You will need to carry this documentation in the glove box at all times, the mere failure of which alone can result in an arrest and possible conviction.

There is discussion of closing the Car Dealer Loophole, through which private individuals sell cars to friends without going through an FAL.  It is important we have these background checks.  Surveys show criminals prefer to buy unlicensed to get around their legal liabilities so they can commit crimes in stolen vehicles, which evidence has proven for many years to be true.

Some vehicle law convictions will result in loss of your driving privileges forever.  This includes reckless operation, drunk driving, an incorrect bumper height or attachment, or the wrong type of exhaust.  Collisions may also result in permanent loss of driving, if injury occurs and negligence is proven.  In addition, any felony conviction of any kind--even tax evasion--will mean permanent loss of your driving privileges.  In these cases, it will even be illegal to ride or sit in a friend's car.

There is also discussion of prohibiting brightly colored vehicles. Vehicles are transportation, not toys, and should not be marketed in a way that suggests they are intended for casual use. It is important that everyone be aware of the dangerous nature of cars.

In the future, we may have to consider large displacement engines (anything over 2.5 liters) and transmissions with more than three speeds as being High Performance Items to be added to the federal registry.  There will be a window during which you can register your items for $2000 each, provided you meet the background check.  Otherwise, you will have to immediately surrender them to an FAL/SOT to dispose of on your behalf.  Operating an unlicensed HPV after this date will result in confiscation and destruction of the vehicle, and the 10/$10,000 punishment.

These laws and regulations are due to drunk drivers, reckless drivers and other criminals.  The automobile community should be glad it is allowed to exist at all, given all the deaths and environmental damage caused by these vehicles.

The president said today that he strongly supports your right to own and drive basic, standard vehicles for farm use and carpooling. But he and many other people have made it clear that eventually – maybe this month – we need to cease all manufacturing of such high powered automobiles for the civilian market.

Eventually, we need to move away from the notion that owning and operating a vehicle is a right and entitlement, and limit it to people with a proven, bona fide professional need.  There are plenty of trains and buses for normal people.  This is how most civilized nations are moving and is not a violation of your right to travel.

©2013 by Michael Z. Williamson www.MichaelZWilliamson.com
Permission to share granted for non profit purposes as long as this notice is included.

Cars are involved in 50% more deaths than guns. About 1/3 of car fatalities involve a driver under age 21. Most lethal car accidents involve multiple casualties. If it's unreasonable to allow someone under 21 to handle a handgun, it is positively insane to allow them behind the wheel of a car, with 6 million times the potential energy, where a SINGLE error or act of will can kill dozens. 

No reasonable person can object to raising the driving age to 21, and improving our background checks--no one with a history of mental illness or psychotropic drug use should ever be allowed to drive a car. Likewise, anyone with a history of anger-related violence is a threat to those around them.

Ultimately, we need to ask the hard question: Who really NEEDS a car? Certainly urbanites with access to mass transit have no need for a personal vehicle, given the inherent dangers and cost to society.

The fallacious response to this is to argue that "cars aren't meant to kill." But, if they are not meant to, but are 50% more lethal than handguns, no reasonable person can argue against tighter restrictions.

My point about the "Second Amendment isn't absolute, of course it doesn't apply to nukes" argument is it's a straw man, that's always presented for reductio ad absurdum, and a slippery slope.
 
"Of course no one would defend the right to own a nuke," but then the next statement, always implied and usually stated is, "So since the right is not absolute, let's see how far we can shove it up your ass and claim 'reasonable.'"  To such people, nukes are not "reasonable" and neither are tanks and planes and artillery and machine guns and "Deadly semiautomatic weapons of mass destruction killing machines that rapidly and accurately spray fire from the hip and can kill 30 kids in a matter of seconds from a high capacity clip."
 
No facts, just bullshit, dishonest soundbites and attempts to blame close to 100 million honest people for the actions of a less than 10, and to compare the ability to wipe out cities to the ability to defend one's home.
 
Yes, and we also need to do something about the Jewish Bankers who own the media and finance and governments, yadda yadda.  After all, they killed Jesus.
 
And don't forget that because of liberals, illegal aliens cross our southern border every night to unplug our comatose women.
 
Oh, and all liberals want to send everyone to gulags, and all free speech activists endorse child porn.
 
And most blacks are drug dealers and hookers.
 
So, yes.  I have a right to own a nuke.  While you jabber in mock fear over the unlikelihood of that ever happening, keep in mind that a rifle, or even a machine gun, isn't a millionth of a nuke.  Trying to play that card just makes you look like a panicky idiot.

My point about the "Second Amendment isn't absolute, of course it doesn't apply to nukes" argument is it's a straw man, that's always presented for reductio ad absurdum, and a slippery slope.

"Of course no one would defend the right to own a nuke," but then the next statement, always implied and usually stated is, "So since the right is not absolute, let's see how far we can shove it up your ass and claim 'reasonable.'"  To such people, nukes are not "reasonable" and neither are tanks and planes and artillery and machine guns and "Deadly semiautomatic weapons of mass destruction killing machines that rapidly and accurately spray fire from the hip and can kill 30 kids in a matter of seconds from a high capacity clip."

No facts, just bullshit, dishonest soundbites and attempts to blame close to 100 million honest people for the actions of less than 10, and to compare the ability to wipe out cities to the ability to defend one's home.

Yes, and we also need to do something about the Jewish Bankers who own the media and finance and governments, yadda yadda.  After all, they killed Jesus.

And don't forget that because of liberals, illegal aliens cross our southern border every night to unplug our comatose women.

Oh, and all liberals want to send everyone to gulags, and all free speech activists endorse child porn.

And most blacks are drug dealers and hookers.

So, yes.  I have a right to own a nuke.  While you jabber in mock fear over the unlikelihood of that ever happening, keep in mind that a rifle, or even a machine gun, isn't a millionth of a nuke.  Trying to play that card just makes you look like a panicky idiot.