SACRAMENTO — A California law requiring gun manufacturers to adopt a bullet-tracing technology has been held up for a decade by legal challenges and concerns that it is not technically feasible.

A San Francisco legislator now is pushing the firearms industry to comply by proposing to scale back standards for the technology, known as micro-stamping, and remove older gun models from the market.

On Monday, Assemblyman David Chiu introduced AB2847, which would require that semiautomatic pistols sold in the state leave a single unique imprint on bullets that are fired — rather than two, as currently required. The marking, which reveals a gun’s make, model and serial number, is meant to help law enforcement investigations.

Under the measure, for each new gun model introduced in California with the micro-stamping technology, the state attorney general would remove three that do not meet the standard from a list of handguns certified for sale.

“It creates a mechanism for unsafe guns to be phased out and safer guns that assist with crime-solving to enter the market,” said Chiu, a San Francisco Democrat.

California originally passed its micro-stamping requirement in 2007, calling for gun manufacturers to incorporate the technology within three years. Supporters argued it would help police trace bullets to their source and connect crimes where the same weapon was used, while the industry countered that micro-stamping was unreliable and could be undermined by dropping bullet casings from another weapon at a crime scene to confuse officers.

But the law has not yet had any practical effect: It was delayed for years as the state waited for a patent held by the inventor of the technology to expire. Then, in 2014, the National Shooting Sports Foundation, a gun industry trade group, and others went to court to challenge the standards that they said could never be met.

Even though the state Supreme Court ultimately upheld the law, manufacturers simply stopped introducing new models to the California market and continued to sell pistols without micro-stamping technology that remained on the certified handguns list.

During the case, gunmakers acknowledged micro-stamping was possible, but said it couldn’t be done in two separate places.

Chiu said that by reducing California’s requirement to one marking — etched by the firing pin as it strikes the back of the bullet when the gun is fired — he was “calling their bluff” and removing their excuse to “boycott the law.”

“Their argument that they can’t do this goes away,” he said.

If new models finally became available in California, Chiu said buyers would also have access to guns that have undergone other safety improvements, such as indicators that show when a gun is loaded to reduce the chances of accidental shootings.

But Mark Oliva, director of public affairs for the National Shooting Sports Foundation, said micro-stamping remains unworkable. He said the etching on a firing pin does not provide a legible imprint on every bullet casing and can easily be removed with sandpaper or by switching out the engraved firing pin with an unmarked spare.

“It doesn’t work every time,” he said. “There are better ways to address the crime problems that California has than putting new requirements on manufacturers.”

Oliva said the micro-stamping requirement is already infringing on gun rights in the state by choking off access to semiautomatic pistols as older models fall off the certified handguns list. He said continuing to pursue the “failed technology” of micro-stamping amounts to an empty gesture by lawmakers.

“They don’t seem to hear about a gun control idea that they don’t love,” he said.

Alexei Koseff is a San Francisco Chronicle staff writer. Email: alexei.koseff@sfchronicle.com Twitter: @akoseff