Rolando resident Wendy Hauffen bought her first AR-15 five years ago.
"The magazine holds 10 rounds just like a standard handgun because in California, we're limited to 10 rounds," said Hauffen.
Hauffen, a member of San Diego County Gun Owners, says state requirements actually make an AR-15 slower to load than a handgun. With the required so-called bullet button feature, gun owners need a tool like an allen wrench to release the magazine.
But anti-gun violence advocates say the rifle is still more dangerous than a handgun.
"It's designed to be more accurate. It's designed to project a bullet faster and more lethally," said Ron Marcus, Director of Public Outreach for San Diegans for Gun Violence Prevention.
Starting last year, state law extended the assault weapons ban to include the sales of the AR-15 with the bullet buttons. Owners can still keep their AR-15s, but they have to register the gun with the state by June.
"If a gun is used in a crime, we need to be able to know how it got into the possession of the person who has it," said Marcus.
"I don't think it's going to be effective at all...the law-abiding citizens are following the law," said Hauffen. "The bad guys won't be registering their guns."
Hauffen says registering the gun at the initial purchase is sufficient, but Marcus points out some transactions, like sales between private sellers and family, are hard to trace.
State officials haven't released numbers, but it's estimated there are thousands - if not tens of thousands - of legally owned AR-15s in California.