SACRAMENTO — Major gun legislation signed into law Friday by Gov. Jerry Brown will force firearms owners to turn over their high-capacity ammunition magazines and make California the first state to require background checks to buy bullets, undercutting a November ballot initiative that seeks to do the same.

The governor acted on a package of 11 bills that aim to keep Californians safer from deadly gun violence less than 24 hours after the Democratic-controlled Legislature approved the measures after heated debate about the Second Amendment and what it will take to stop the next mass shooting.

On Friday, researchers who study gun violence said the new laws could have a huge impact on public safety.

“These new policies could have substantial effects, and rigorous evaluations will be needed,” said Garen Wintemute, a gun policy expert at UC Davis. He noted that the research can now be facilitated by the firearms violence research center lawmakers voted last month to create within the University of California.

Brown’s decision to veto almost as many bills as he signed did little to pacify outraged pro-gun groups that believe the measures were improperly rushed through the legislative process in the wake of the San Bernardino and Orlando massacres. One reason was that the governor signed the most controversial bills.

In statements, the National Rifle Association and other gun rights groups condemned the new laws as “draconian” and “Stalin-esque,” even suggesting that Californian residents consider disobeying them.

“We expect mass noncompliance with these laws and encourage good, peaceful Californians to carefully consider the risks of voluntarily identifying their firearms, magazines and ammunition to law enforcement officials, especially the California Department of Justice,” said Brandon Combs, president of the Firearms Policy Coalition. “The government would be wise to remember that there are more California residents with guns than there are government officials to take them away.

“To coin a phrase, ‘Come and take it.’ “

Along with the ammunition bills he signed, Brown endorsed legislation that will prohibit long guns with “bullet buttons” that make it easier for shooters to reload, strip a resident’s gun rights for 10 years as punishment for knowingly filing a false report of a gun loss or theft, and limit the lending of guns to family members who have not completed California’s extensive background checks.

The bills will surely spark some legal challenges before they take effect in January.

Amy Hunter, a spokeswoman for the NRA’s Institute for Legislative Action, released a statement Friday saying the group is “prepared to pursue all options moving forward — legal, legislative and political.”

“These bills will make no one safer,” Hunter said. “They only add another layer of laws that criminals will continue to break.”

The governor, however, seems to believe the opposite is true.

“My goal in signing these bills is to enhance public safety by tightening our existing laws in a responsible and focused manner, while protecting the rights of law-abiding gun owners,” Brown wrote in a signing statement he penned Friday before leaving for a two-week vacation in Europe.

So far, it’s unclear what impact the new laws will have on pro-gun groups’ approach to defeating an initiative sponsored by Lt. Gov. Gavin Newsom, which will appear on the November ballot as Proposition 62.

Hunter said Friday the NRA had just started discussing its strategy.

Asked Craig DeLuz, director of public and legislative affairs for the Firearms Policy Coalition. “Does the initiative do anything now? We’re still taking a look at all of it.”

Proposition 62 would regulate all ammunition sales like firearms sales; require licensed vendors to report ammunition theft within 48 hours; outlaw possession of large-capacity magazines; make theft of a firearm a felony; and create new court processes to ensure that firearms are surrendered by people upon conviction of serious crimes.

But because Brown signed Senate President Pro Tem Kevin de León’s Senate Bill 1235, regulating ammunition sales, and Sen. Loni Hancock’s Senate Bill 1446, outlawing possession of magazines with more than 10 rounds, voters will only get to choose whether to enact the new court process, require reporting of lost or stolen ammunition and make the theft of all firearms a felony.

California’s 1999 update of the quarter-century-old assault weapons law banned the importation, manufacture and sale of large-capacity magazines. Now, because of the Hancock measure, possession of the magazines is banned as well, requiring owners to sell them to out-of-state owners, move them out of California or turn them in to law enforcement officials.

Dismissing criticism that the bill signings have made his ballot measure redundant, Newsom on Friday called the governor’s actions “steps in the right direction” that would only grow into a “giant leap forward for public safety” if voters pass Proposition 62.

“Now, with the Safety for All initiative, voters will finally have a chance to take matters into their own hands and keep the momentum going with bold reforms that build on these achievements and go well beyond,” Newsom said in a statement.

Assembly Bill 1176, authored by Assemblyman Jim Cooper, D-Elk Grove, also sought to make theft of all firearms a felony by placing a measure on the ballot to amend 2014’s Proposition 47, which downgraded many nonviolent crimes from felonies to misdemeanors. But Brown vetoed Cooper’s bill so voters in November won’t be asked the same question twice.

Brown vetoed five of the 11 gun bills the Legislature sent him, citing concerns that the proposals were premature or could have unintended consequences.

Lawmakers passed 12 gun bills on Thursday, but the Assembly held AB 857, authored by Cooper, which would require people who manufacture “ghost guns” at home to apply to the Department of Justice for a unique serial number before assembling the firearms. The governor will consider that bill later this summer.

Assembly Bill 1674, authored by Assemblyman Miguel Santiago, D-Los Angeles, would have extended the law limiting the number of handguns residents can buy each month to long guns. Brown called the bill “well-intentioned” but wrote in a veto message that he couldn’t sign it because it would unfairly limit private firearms sales.

He also rejected AB 2607, which would have expanded the group of people who may request a gun violence restraining order to include mental health workers, employers, co-workers and school employees; SB 894, which would have made it a crime to fail to report a lost or stolen gun within a few days; and AB 1673, another bill that sought to eliminate the proliferation of “ghost guns.”