Colorado lawmakers will again seek to ban the sale of certain types of semiautomatic firearms in the coming legislative session, embracing a new approach after more sweeping assault weapons bans died in the state Capitol in recent years.

The new bill spearheaded by Democrats is aimed at building upon existing gun laws by prohibiting the sale, manufacture or purchase of semiautomatic weapons that use detachable magazines. It is set to be introduced in the early days of the legislative session, which begins Wednesday.

Detachable magazines feed ammunition into the gun and can be swapped out when empty. The measure would also ban rapid-fire trigger activators and bump stocks, which are components that increase the fire rate of semiautomatic rifles and were infamously used in America’s deadliest mass shooting, in Las Vegas in 2017.

The bill, sponsored by Centennial Democrat Sen. Tom Sullivan, would not prohibit possession of the targeted firearms, and anyone who possessed the weapons before a ban went into effect could keep them.

The measure would level criminal penalties — as well as the loss of licensure — against sellers who violated it.

Sullivan cast the bill as a way to enforce the state’s 11-year-old ban on high-capacity magazines — which, he said, are still sold in Colorado despite the prohibition. The components were used in both the Boulder King Soopers shooting and the Club Q shooting in Colorado Springs, Sullivan said.

“So instead of walking into the King Soopers with multiple magazines that (the shooter) just switched out and kept on firing, he would either have to stop and manually reload, which gives law enforcement and the public the ability to take some kind of an action … or he would have to walk in there with multiple AR-style weapons with attached magazines,” said Sullivan, whose son, Alex, was killed in the 2012 Aurora movie theater shooting, in an interview.The proposal is not a ban on certain semiautomatic rifles referred to as assault weapons, though its parameters would prohibit the sale of a wide swath of high-powered guns colloquially considered to be in that category. Sullivan has previously opposed efforts by Democratic lawmakers to ban assault weapons at the state level, and one such attempt passed the House before dying in the Senate last spring.

Sullivan reiterated his opposition to a state-level assault weapons ban, though he said he supported a nationwide prohibition.

Those types of firearms could still be sold under his bill, albeit in different form: If manufacturers and gun owners want to continue selling and using the weapons, Sullivan said, they would need to adjust to firearms that can only be loaded slowly, bullet by bullet, from the top of the weapon — not through detachable magazines.

Sullivan criticized firearm manufacturers and dealers for continuing to sell high-capacity magazines in the state, and he questioned why law enforcement had not done more to proactively crack down on their sale. The effort to ban bump stocks comes after the U.S. Supreme Court struck down a Trump administration ban on the components, which drew national scrutiny after the Las Vegas mass shooter fired more than 1,000 bullets in 11 minutes in 2017.

The proposal does not cover standard handguns or shotguns, though the prohibition would include the type of pistol used in the Boulder King Soopers shooting that left 10 people dead in March 2021.

The new bill will be co-sponsored by Democratic Reps. Andrew Boesenecker and Meg Froelich. Boesenecker co-sponsored the state licensure bill last year, while Froelich and Sullivan backed the measure to increase the investigative bureau’s budget to pursue illegal gun sales.