The two rifles were not specifically listed among the models outlawed under California's famously tough gun laws, and as long as each included a minor design change affecting how bullets are loaded into the weapon they would have been legal.
California limited access to high-powered, military-style rifles in 1989 and lawmakers passed further restrictions in 2000, when they banned specific types of AR-15 and AK-47 style rifles. Included in the ban were rifles that can use detachable ammunition magazines that hold more than 10 rounds and have other characteristics. Ammunition magazines that hold more than 10 bullets are also outlawed.
California's law prompted the gun industry to start marketing military-style rifles with so-called bullet buttons, a sort of sleeve that blocks quick access to the release button. Users can use the tip of a spare bullet or a tool to release the gun's magazine, although a small magnet can be attached to the button so that users can quickly press it using just their finger.
Law enforcement officials recovered a Smith and Wesson M&P-15 and an A15 made by Defense Procurement Manufacturing Services Panther Arms and two handguns after Wednesday's mass shooting at a disability services center and a shootout with a married couple suspected of carrying out the attack. Both rifles are sold with bullet buttons.
The assistant director of the FBI's Los Angeles office, David Bowdich, said Thursday that Syed Rizwan Farook legally bought the handguns. He said the rifles were bought by someone else though he did not provide any other details. The Bureau of Alcohol, Tobacco, Firearms and Explosives said earlier that all four guns were legally purchased.