SACRAMENTO, Calif. — Gov. Jerry Brown signed six stringent gun-control measures Friday that will require people to turn in high-capacity magazines and mandate background checks for ammunition sales, as California Democrats seek to strengthen gun laws that are already among the strictest in the nation.

Brown vetoed five other bills, including requirement to register homemade firearms and report lost or stolen weapons to authorities.

The Democratic governor’s action is consistent with his mixed record on gun control. Some of the enacted bills duplicate provisions of a November ballot measure by Democratic Lt. Gov. Gavin Newsom. Some of the vetoed measures also appear in Newsom’s initiative.

“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 one-sentence message to lawmakers.

Gun control measures have long been popular with the Democratic lawmakers who control the California Senate and Assembly. But they stepped up their push this year following the December shooting in San Bernardino by a couple who pledged allegiance to the Islamic State group.

Advocates on both sides of the gun-control debate say California has some of the nation’s strictest gun laws. It is one of six states to get the highest grade from the pro-gun control Law Center to Prevent Gun Violence.

The state’s move to tighten them further comes amid years of gridlock at the federal level, which spawned a tense clash in Washington last week as Democrats camped out on the floor of the U.S. House and shouted down Republicans.

The bills angered Republicans and gun-rights advocates who say Democrats are trampling on 2nd Amendment rights, creating new restrictions that won’t cut off the flow of guns to people intent on using them for nefarious purposes.

“On the eve of Independence Day, independence and freedom and liberty in California has been chopped down at the knees and kicked between the legs,” said Sam Paredes, executive director of the advocacy group Gun Owners of California.

Lawsuits challenging the new laws are likely once they take effect next year, Paredes said.

Brown’s action will require people who own magazines that hold more than 10 rounds to give them up. It extends a 1999 law that made it illegal to buy a high-capacity magazine or to bring one into the state but allowed people who already owned them to keep them.