One of the three guns Adam Lanza used to kill 20 children and six adults at an elementary school in Newtown, Connecticut, was a military-style semiautomatic rifle known as an AR-15. That surprised and shocked a lot of people unfamiliar with America's gun culture. They questioned why such weapons are available and why anyone would need them.
"Personally I don't know how any ordinary citizen can justify owning an automatic or semiautomatic gun," writes CNN commenter Mark Smerkanich. "Can't we leave those guns to the trained military?"
Self-described gun owner Julie Jones-Hawkins comments, "I ... fully support a ban on rapid-fire weapons. Any weapon that can take out an entire kindergarten class is a problem."
Here are five reasons many gun owners say they want military style rifles:
'Some people play golf, others bowl. I shoot'
"Every month or so I take my guns out to the range and shoot. It's thrilling, exciting and a great way to vent," says Christopher L. Kirkman, a Florida-based military-style gun owner.
Kirman was one of more than 100 gun enthusiasts who shared opinions on CNN iReport about owning firearms that would have been banned under the now-expired 1994 federal weapons ban.
"Sure, I could try to say that the reason I own these guns is self-defense, but the truth of the matter is that, although they will technically serve this purpose, they are not why I own them," he says.
Michigan gun owner Ethan Daniels describes his enthusiasm for his rifle more succinctly, saying, "I like to shoot, and that is one heck of a fun carbine to plink with."
Background can factor into a gun owner's choice of weapon. "The AR-15 is what I am used to from my extensive training as an airborne infantryman," writes Nathan Lee. "Because of my training, it's what I feel the most comfortable with."
Another reason for these guns is hunting. The AR-15 is a "good hunting platform. I've hunted coyote with it," says CNN iReporter MVR155, who owns two of the weapons. He asked to remain anonymous.
Owners of military-style rifles also use them to hunt deer and other game. But some states have banned the AR-15 and its .223 caliber for deer hunting.
It may not be the best or most important reason, but military-style weapons often appeal to the enthusiast side of the American gun owner. Just like many car lovers who dream of owning a Lamborghini, many gun owners get excited about the idea of owning an AR-15.
"There are people who buy certain types of firearms because they have a certain image -- the AR-15 is one of them," says Austin Nikel, a former AR-15 owner in Boulder, Colorado.
"One thing about this country is how Hollywood has glorified the image behind those certain types of weapons. A lot of guys grow up with GI Joe, and that image is extremely attractive. It grabs you and affects you.
"A lot of people buy the AR-15 because, well, it's cool."
Apparently it wasn't cool enough for Nikel to hold on to. He ended up selling his AR-15 to his father.
'A part of history'
"Since coming of age -- and in the decades since -- I have collected many different firearms, some of them historical pieces, some for sport, some of them even the so-called 'assault weapons' that are now a controversy," says iReporter Hrothgar01.
"Guns like these are as much a part of the history of this country as the muskets carried by pioneers, the rifles toted by doughboys in the trenches, and the other arms that have served and protected throughout the years. To hold one in your hands, appreciate its history and design, and to be able to take that piece of history to the range and work -- it is a feeling that many people in this debate do not understand or appreciate."
'Protecting my family'
"I believe the foremost person responsible for protecting my family and myself is me," writes iReporter ShortyDoowap, who owns a pair of AR-15s. "These rifles provide me with the tools to perform that duty. I don't own these guns to target shoot, though I do that with them. I don't hunt with them, though I could in a pinch."
Parks says he "would not hesitate to use one to simply defend my home and family from a single intruder if it became necessary."
In some home-protection situations, fans say military-style rifles are generally more accurate than handguns. Rifles are generally easier to learn how to shoot, say military-style rifle owners.