SACRAMENTO -- In California, the state with the nation's toughest gun laws, you couldn't walk into a gun shop and buy the AR-15 military-style assault rifle used in the massacre early Friday at a Colorado movie theater.

Fully-automatic and military-style assault weapons that fire more than 10 rounds at a time, like the AR-15, are against the law in the Golden State. But the other weapons that the 24-year-old shooter used to kill 12 moviegoers and wound as many as 50 others are legal to sell and possess in California.

Authorities say James Eagan Holmes, a California native, used four guns in his attack: an AR-15 assault rifle, a Remington 12-gauge shotgun and two Glock pistols. The guns were purchased legally over the last several months at two national chains in Colorado, officials said.

Gun owners in California use variations or knockoffs of the AR-15 assault rifle, but have been prohibited from purchasing, selling or owning assault weapons since 1989, when the state became the first in the nation to ban military-style assault weapons in the aftermath of the Stockton schoolyard shooting that left five children dead and 29 others wounded.

"They may look like AR-15s, but they are not AR-15s," said Mike Fournier, co-owner of the San Jose-based Gun Exchange. "It is a named, registered assault rifle and you just cannot buy one."

California has approved 45 gun-control laws since then, while laws protecting the rights of gun owners have flourished around the rest of the country.

Any semi-automatic rifle must be outfitted with a magazine locking device that prevents shooters from re-loading quickly, experts said. Under California's assault-weapons ban, the maximum number of rounds allowed per magazine is 10.

Semi-automatic guns are allowed in California, though gun owners are not allowed to carry them -- or any other guns -- concealed.

In Colorado, concealed weapons are allowed for those who purchase a permit, though Cinemark Theaters, the owner of the Century 16 theater in Aurora, forbids anyone other than law enforcement to carry weapons.

Critics said the death toll could have been minimized if gun owners with concealed carry weapons permits were allowed to bring their weapons to the theater.

As details emerge about Holmes, 24, a picture is forming of a troubled graduate student in neurosciences who had little contact with fellow students and was preparing to leave his medical studies.

It is an eerie parallel to the alleged shooter who killed seven people in April at Oikos University in Oakland. One L. Goh, a disgruntled and troubled student, had recently been kicked out of school.

Neither had trouble gaining access to guns, because neither had a known history of mental illness, which would have prevented them from obtaining weapons in both states.

Police said that Goh, a 43-year-old South Korean immigrant, used a legally purchased .45-caliber semi-automatic pistol. They said the gunman had four fully loaded magazines, each with eight rounds of ammunition. Under California's assault-weapons ban, the maximum number of rounds allowed per magazine is 10.

California law prohibits those with a criminal past, a history of being hospitalized with a mental illness, restraining orders based on domestic violence and anyone younger than 18 from owning firearms.

California goes beyond federal law in requiring background checks on individuals who seek to purchase firearms at both gun shops and gun shows. It also requires a 10-day waiting period for handguns and rifles.

The tide has turned against gun-control advocates in recent years. After the federal assault-weapon ban expired in 2004, there have been no serious legislative attempts to restore the law, which banned 19 models of assault weapons, including some semi-automatic handguns. Magazines were limited to 10 rounds.

Congress' reluctance to address gun laws was most apparent after the January 2011 shooting in Tucson, Ariz., that killed six and injured 13, including Rep. Gabrielle Giffords. Gunman Jared Loughner used a semi-automatic with more than a 30-round magazine, legal in Arizona and allowed after the federal assault-weapons ban expired.

In the wake of the Tucson shootings, national polls showed broad majorities of adults favored bans on semi-automatic guns. But even in ultra-blue states such as California, there is no movement to ban semi-automatics, which are also used in hunting.

Last year, Gov. Jerry Brown signed a handful of gun-control bills, including one that banned most people from openly carrying an unloaded firearm. But Democrats have not had any luck moving legislation that would track the sale of ammunition or large-capacity ammunition magazines -- largely because of the costs associated with setting up a registry.

Contact Steven Harmon at 916-441-2101. Follow him at Twitter.com/ssharmon. Read the Political Blotter at IBAbuzz.com/politics.

California vs. colorado on gun laws
Here's a comparison between California and Colorado gun laws:
Assault weapons
Colorado law: Allows ownership of assault weapons, though Denver can restrict them.
California law: Prohibits ownership of assault weapons unless acquired before 1989. Semi-automatic guns, however, are not considered assault weapons and are allowed as long as they carry magazines of less than 10 rounds.
Background checks, waiting periods
Colorado law: Requires background checks for firearms purchased at gun shows.
California law: Requires a background check and 10-day waiting period on both handguns and rifles; gun shows are not exempt
Concealed weapons
Colorado law: Concealed weapons require a permit.
Local law enforcement retain the right to deny concealed carry permits on reasonable doubt.
California law: Allows concealed-weapon permits, but the number of permits issued varies widely by jurisdiction.
Open carry
Colorado law: Allows anyone who owns a gun to carry openly.
California law: Prohibits individuals from openly carrying weapons.