Gov. Jared Polis on Friday signed a measure banning “ghost guns,” the fifth major gun legislation from Colorado’s 2023 legislative session.

Polis called for a ban on ghost guns — unserialized weapons that can be made from kits and on 3D printers — in his January State of the State address. That call was also echoed by the mayors of Colorado’s three largest cities: Mayor Mike Coffman of Aurora, Mayor Michael Hancock of Denver and Mayor John Suthers of Colorado Springs, in a letter published by The Gazette in December.

Coffman was on hand for Friday’s signing ceremony, along with district attorneys from Denver, Jefferson. Boulder and Adams counties and the 18th Judicial District.

Senate Bill 279 is set to follow four other major measure that supporters say would rein in gun violence in Colorado. The governor signed them in April:

• Expanding the state’s “red flag” law, which allows district attorneys, higher education faculty and K-12 teachers and medical professionals to seek extreme risk protection orders.

• Allowing victims of gun violence to sue firearms dealers and manufacturers in civil court, overturning a 2000 law granting immunity to firearms dealers that gun control advocates called one of the strictest in the nation.

• Creating a three-day waiting period for delivery of a firearm after purchase or transfer.

• Raising the age for purchase of a firearm from 18 to 21, although the measure allows for possession of a firearm by those under 21 years old.

The latter two are the subject of a lawsuit filed against the state by gun rights organizations.

SB 279 bans the manufacture and possession of unserialized frames and receivers, the outer shell that holds the components for a gun, a move that proponents hope would curb the proliferation of ghost guns, which can be assembled with kits that include all or part of a gun, as well as created through 3D printers.

However, the bill does not ban the sale of kits that do not include the frames or receivers or components that can be used to create a gun on a 3D printer, so long as the components don’t include the frame or receiver.

The bill also creates a new misdemeanor charge for possessing an unserialized firearm, which can be made with kits, or even with 3D printers.

SB 279 provides an opportunity for owners of ghost guns to get serial numbers added onto their firearms. That can be done by any licensed dealer, but it would also require a background check under existing state law. That window expires at the end of the year.

“None of these bills interfere with the legal use of weapons,” Polis said.

“I believe [SB 279] will make Colorado safer with compromising the right of law-abiding citizens to own firearms,” Coffman said.

Second Amendment proponents said the package of gun bills pushed by Democrats this year infringe on Coloradans’ right to keep and bear arms, arguing they would turn law-abiding residents into criminals.

When the governor signed the four gun bills earlier, House Minority Leader Mike Lynch, R-wellington, called it a “historically dark day.” Lynch said most Colorado gun owners follow the law but that Democrats want to punish them for the criminal or tragic actions of a few.

At today’s signing ceremony, Brian Mason, the district attorney for the 17th Judicial District in Adams County, said he didn’t know 10 years ago what a ghost gun was. Now, it’s a crisis in every community, state and across the country, he said.

He also called the coalition that backed the bill, which involved Republicans and Democrats in many communities, “a special collaboration” that isn’t seen very often.

Notably, no Republicans in the General Assembly voted for any of the five measures.

Polis also signed a proclamation for the ninth annual National Gun Violence Awareness Day, surrounded by students from East High, who joined him in reading the proclamation.

“We talked to our legislators, marched across town, registered to vote, testified and helped pass common sense gun laws,” said Julia Knox, an East High student.

The votes of lawmakers “showed they hear us, represent us and will fight for us.”

In a statement Friday, Polis said: “I am proud of the achievements reached this year to improve gun safety and reduce crime, but the work is not done.”

“In order to make Colorado one of the top ten safest states, we must continue to come together to build on these public safety accomplishments,” he added.

What that could look like is a more robust gun violence prevention office, and “permit to purchase,” a license that must be issued prior to buying a gun.

Rep. Meg Froelich, D-englewood, a co-founder of the legislative gun violence prevention caucus, weighed in favor of an enhanced office of gun violence prevention that would help lawmakers look at statistics and where people who shouldn’t have guns are getting them.

She also spoke in favor of the “permit to purchase” law.

In Oregon, where voters approved the concept via ballot measure in 2022, an applicant must first complete a certified firearms safety course and then get a permit application with local law enforcement, which includes a national and state background check.

“Because the ATF does not enforce state law, we need mechanism to enforce the good work we’ve done,” Froelich told Colorado Politics Friday.