Gun owners in Washington state will soon see their options for ammunition magazines severely diminished.

Governor Jay Inslee (D.) signed Senate Bill 5078 into law on Wednesday. The bill will prohibit the manufacture, distribution, and sale of magazines that can hold more than 10 rounds of ammunition. It will go into effect on July 1.

“It restricts access to large-capacity magazines in Washington to help reduce the number of horrific fatalities and injuries in mass shooting events,” the Governor said during the signing. “We know these types of policies are effective and we know that they save lives. I’m happy to sign this bill.”

The Governor’s signing of the bill represents a major victory for gun-control advocates in Washington state. Democratic lawmakers have attempted to pass a magazine-capacity restriction in six different legislative sessions in recent years only to see those attempts fall short in the face of backlash from Washington gun owners. Now it appears the tide is turning for the prospect of gun control in a state that boasts high levels of gun ownership, despite its Democratic lean.

Inslee was joined by Attorney General Bob Ferguson (D.), the chief proponent of the magazine ban, and several gun-control advocates for the signing of the legislation. They praised the Governor’s support on the issue.

“Today is a proud day for gun violence survivors, advocates, volunteers, and legislative champions in Washington state,” Kim Gatbunton, a volunteer leader with Moms Demand Action, said during the signing. “I’m grateful for Governor Inslee’s leadership in this movement and for a day when we can end gun violence in the Evergreen state.”

Gun-rights advocates have mobilized in response to the Governor’s signature. Alan Gottlieb, founder of the Washington-based Second Amendment Foundation, told The Reload his group plans to challenge the magazine ban in court.

“The Second Amendment Foundation will definitely file a lawsuit against the magazine ban,” Gottlieb said. “Our attorneys are reviewing the other two bills.”

Many gun owners have already been proactive in anticipation of the Governor’s signature of the sales ban. Because Senate Bill 5078 does not prohibit possession of “high-capacity” magazines, gun owners and major retailers alike have launched into a concerted effort to stock up before the ban goes into effect.

Manufacturers Palmetto State Armory and the Washington-based Aero Precision publicly declared that they will be prioritizing ammunition magazine orders to residents of Washington state.

“With the passing of Washington State’s unconstitutional law targeting standard capacity magazines, it is more important than ever for Washington State citizens to stock up on mags,” the manufacturer Palmetto State Armory posted on the company’s Facebook page. “All magazine orders placed from Washington State with Palmetto State Armory with ship out immediately and receive priority over all other orders.”

In addition to the magazine prohibition, Governor Inslee also signed two other gun control bills into law on Wednesday. House Bill 1630 bans the carrying of firearms in certain locations, including on school grounds, city council meetings, and election offices. The other bill, House Bill 1705, will prohibit unserialized firearms and firearm components in an effort by the state to target so-called ghost guns.