They’ve banned high-capacity magazines and cracked down on assault weapons. They’ve made it so Californians have to pass a background check to purchase a gun and ammunition. They’ve prohibited buyers from having ammo or “ghost” gun parts shipped directly to their homes.

When it comes to gun laws, California’s legislators have passed some of the most stringent regulations in the country, checking off nearly every box on national gun control advocates’ wishlist.

A mass shooting early Sunday that left six dead and 12 wounded just a block from the Capitol — the very building where these laws were enacted — immediately prompted new calls for legislation to curb gun violence, from California elected officials and gun-control advocates across the nation.

“The scourge of gun violence continues to be a crisis in our country, and we must resolve to bring an end to this carnage,” Gov. Gavin Newsom, who’s already signed 15 gun-control laws, said Sunday in a prepared statement.

The call for action on the federal level reached as far as the White House.

“Ban ghost guns,” President Joe Biden said, expressing his sorrow for the Sacramento victims. “Require background checks for all gun sales. Ban assault weapons and high-capacity magazines. Repeal gun manufacturers’ immunity from liability.”

But what else can California’s lawmakers do to restrict guns that they haven’t already done — and have their laws survive the inevitable challenge by Second Amendment advocates?

Even before Sunday’s shooting, Democratic legislators planned to do more. One new bill, introduced by state Senator Bob Hertzberg, D-Van Nuys, would give citizens the “private right of action” to sue gun manufacturers and suppliers. The bill, SB 1327, is modeled after an anti-abortion law enacted in Texas.

State Sen. David Min, D-Irvine, introduced Senate Bill 915, which would prohibit the sale of firearms or ammunition on state property, effectively ending gun shows on 73 state-owned fairgrounds. Previous efforts on a blanket-ban on gun shows at fairgrounds have failed.

“These are all practical actions we can take today to stop gun violence,” Hertzberg said Sunday.

But the fact is, the recent legislation pending in California is relatively modest compared to some of the sweeping reforms that gun-control advocates are demanding in other states and on the federal level — simply because most of the toughest curbs are already part of California law.

Among other things, nationwide advocates are seeking to have all private-party gun sales subjected to federal background checks, which they call the “gun-show loophole.” They also want to see the nationwide assault-weapons ban, which expired in 2004, revived. Both of those laws are in effect in California.

Advocates for gun owners say there isn’t much else California can do, given the protections for gun ownership enshrined in the Bill of Rights.

“Here in California, we have done everything we could possibly do to control guns,” said Sam Paredes, who runs the Sacramento-area organization Gun Owners of California. “Everything short of banning (guns), and they know they can’t do that.”

Paredes said lawmakers are gliding over the real issues that drive gun violence.

“Is it mental? Economic? Medical? What is it? They won’t go there. Their knee-jerk reaction is to go after guns,” Paredes said.

California has 107 different gun-control laws on the books, more than any other state, according to a database maintained by the Boston University School of Public Health. Massachusetts is No. 2 at 103.

Still, lawmakers say Sunday’s bloodbath near the Capitol shows there’s more work to do in a state where an estimated 7 million people live in a home where guns are present.

“What a sickening, senseless loss of life,” said California Assembly Speaker Anthony Rendon on Twitter. “It’s an epidemic, and we need #GunReform now to stop it.”

Sacramento Mayor Darrell Steinberg, speaking a block from the scene, said, “Thoughts and prayers are not nearly enough …. This senseless epidemic of gun violence must be addressed.” He called for tougher laws on assault weapons, even though it wasn’t immediately clear what type of gun was used Sunday.

The 15 gun-control laws Newsom has signed as governor cover an array of restrictions, broad and narrow. AB 1669 requires anyone selling ammo at a gun show to be licensed. SB 61 extends the waiting period on multiple handgun purchases to include semiautomatic rifles. And AB 893 specifically bans any weapons or ammo sales at the state-owned Del Mar Fairgrounds in the San Diego area.

Even if lawmakers do pass more reforms, it’s not a sure bet they’ll survive a legal challenge. A gun-control law Newsom championed as lieutenant governor spent years in legal limbo before finally being upheld by the courts.

California voters in 2016 approved Proposition 63, a sweeping package of gun control reforms that included the state’s ban on possessing so-called “high-capacity” magazines that hold more than 10 rounds. The Newsom-supported initiative also included one of the nation’s first background checks for ammunition purchases.

The law has since been challenged in court, and gun-rights advocates scored some early victories. In August 2020, a three-judge panel of the 9th Circuit Court of Appeals ruled the magazine ban was unconstitutional.

However, last December the 9th Circuit U.S. Court of Appeals ruled that the law was constitutional, after all. Gun-rights advocates said they were likely to appeal to the U.S. Supreme Court.

The state’s ammunition background check process has been challenged as well, and a federal judge in San Diego ruled it was unconstitutional.

The laws remain in effect as the cases make their way through the courts.

Similarly, California’s efforts to close loopholes around assault weapons have faced legal scrutiny.

California banned assault weapons three decades ago. To get around the prohibition, some gun manufacturers began building rifles with “bullet buttons,” devices that allow a gun’s ammunition magazine to quickly disengage with the use of a small tool, usually the tip of a bullet.

In 2016, lawmakers passed a law that banned selling those weapons, but it allowed those who already possessed them to keep them so long as they registered their guns online with the California Department of Justice.

Gun rights advocates sued, and last year, the California Attorney General’s office signed a settlement agreement in federal court admitting the agency gun-registration website was so poorly designed that potentially thousands of Californians were unable to register their assault weapons and comply with state law.

Under the terms of the federal settlement, the state Department of Justice was required to notify each district attorney and law enforcement agency to put on hold “all pending investigations and prosecutions” for those suspected of failing to register their assault weapons. The settlement gave those seeking to register their weapons more time to do so.

California has discovered that its own gun laws are rendered meaningless when someone brings in a weapon from out of state.

In July 2019, three people were shot dead at the famous Gilroy Garlic Festival by a man wielding an assault rifle he’d purchased legally in Nevada just three weeks earlier.

At the same time, recent acts of mass violence show that those intent on committing violence can get around other laws that are supported, at least in principle, by both gun-control and Second Amendment advocates, such as California’s stringent prohibition on people with violent histories being able to acquire guns and ammo.

In late February, 39-year-old David Mora shot his three daughters to death in a Sacramento-area church, along with a man who was supervising a court-ordered visit with the children. Mora then shot and killed himself.

Mora had a domestic violence restraining order that should have prevented him from possessing a gun.

It was among several other recent high-profile shootings in California from people prohibited from having firearms.

On Feb. 2 — less than four weeks before the church shooting — a 21-year-old passenger on a Greyhound bus opened fire on passengers in Oroville, killing one person and wounding at least four others, including an 11-year-old girl. The suspect, Asaahdi Elijah Coleman of Sacramento, had a lengthy rap sheet that should have stopped him from owning a gun.

The man accused last year of killing four people and wounding the mother of a third grader who died in her arms in the Southern California city of Orange had a six-year-old battery conviction that should have prohibited him from possessing firearms.

In 2020, a Madera man fatally shot his estranged wife in front of the couple’s three children. The woman had told law enforcement her husband had a gun, and she detailed the abuse that had gone on. The shooter, however, denied having firearms, and there was little apparent follow-up.

And in November 2017, a deranged gunman named Kevin Janson Neal went on a shooting binge through the tiny community of Rancho Tehama, firing indiscriminately. The man killed five people in the rampage and wounded dozens more, including several students at an elementary school, before he shot himself after a gunfight with deputies.

He, too, was prohibited from possessing weapons but had used a ghost gun — a firearm he built himself.

Experts say that even in a state such as California where support for gun control is strong, it’s always going to be difficult to prevent gun violence.

The reality is there are millions of weapons in circulation, many of them off the books and easily obtained illegally.

There also is no easy way for law enforcement officers to know someone has an unregistered gun.

“You’re never going to completely stop mass shootings in a society that’s awash in guns,” Adam Winkler, a UCLA professor who studies gun access and the Second Amendment told The Bee in February. “It’s just not going to happen.”