Several gun rights advocates are suing to block a new California law that requires additional background checks ahead of ammunition purchases, calling it a violation of Second Amendment rights.

The preliminary injunction, filed by the California Rifle and Pistol Association on Monday in a federal court in San Diego, names Kim Rhode, an Olympic shooter and National Rifle Association board member, as its lead plaintiff.

The text of the injunction refers to the newly-implemented restrictions within Proposition 63, approved by California voters in 2016, as a "scheme" that "goes too far" and must be stopped.

"California ammunition vendors have reported as high as 60% of people who undergo California’s background check do not pass," Rhodes' attorney, Sean Brady, argued in the 34-page motion. "And California has placed the additional, absurd requirement that the very identification it issues is insufficient to undergo the background check, resulting in countless other eligible people being unable to exercise their rights."

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The new law requires anyone who purchases ammunition in California to undergo a background check, at a cost of $1, with every purchase. Those who don’t already have their information in the Department of Justice’s system for these point-of-sale screenings will have to pay up to $20 for an initial screening.

The law also requires that all ammo purchases take place in person. Even online orders must be delivered to a licensed vendor for customer pick-up.

Attorneys for the Fullerton-based gun rights group argued in the injunction that the new law should be shelved, returning California "to the status quo of two years ago, along with the rest of the country" while the parties in the suit litigate the matter.

Although the law received praise from gun control advocates, who said that the additional background checks could help reduce gun violence, the injunction echoed criticisms that some gun owners and vendors expressed before the law was implemented on July 1.

Particularly, the injunction asserted that the new restrictions would make purchases more costly and time-consuming without having an impact on safety.

Some of those criticisms lingered after the law went into effect.

"Even if an eligibility check goes smoothly, the process of selling ammunition now takes at least 4-5 times longer than it did before," said Alex Reyes, a manager at Martin B. Retting, a gun shop in Culver City near Los Angeles, several days after the law went into effect. "I’m sure customers, like dealers, are frustrated at what seems like an ever increasing burden placed by the state directly on law abiding gun owners."

Along with problems with purchasing ammo in stores, the suit alleges that the new law unfairly shuts out-of-state vendors out of California's ammunition market.

Under Prop 63, it became illegal for buyers to bring ammunition purchased out-of-state to California, closing off options for buyers who previously made purchases in Arizona or Nevada.

"California’s ammunition scheme not only prevents out-of-state vendors ... from accessing California customers in a particular manner," the motion reads. "It renders out-of-state vendors’ ability to do business in California entirely dependent on the discretion of their in-state competitors."

While Martin B. Retting, which sells antique weapons as well as modern firearms and ammunition, was not among the eight establishments in California that filed declarations in support of the new lawsuit, Reyes said the gun shop has experienced the effects of the new law.

"We’re seeing a few glitches now and while they might tend to get ironed out with time, our fear is that as ammunition sales return to a more normal pace, the added volume to the system will overwhelm it and minor issues will become major ones," Reyes said earlier this month.

The injunction argues that those issues are already significant enough to warrant action against the "unprecedented restraints" imposed by the new law.

"The entire system has been shown to be an unconstitutionally excessive burden on law-abiding gun owners with little to no law enforcement value," the California Rifle and Pistol Association said on its website.