The movement to ban the purchase or sale of bump stocks, used to convert semi-automatic weapons to automatic ones, has now made its way to the state Capitol.

Tuesday, Democratic Sen. Michael Merrifield of Colorado Springs spoke to reporters about Senate Bill 51, which would ban the purchase or sale of bump stocks or similar devices. Merrifield and Lt. Gov. Donna Lynne spoke at an afternoon press conference about the need for a ban.

The issue arose after the October 1 shooting in Las Vegas, where the shooter used bump stocks to accelerate the speed of his weapons. Fifty-eight people died and 851 were injured. The shooter killed himself before law enforcement could stop him. According the New York Times, the shooter had outfitted 12 of his rifles with bump stocks.

According to the Times, a bump stock “replaces a rifle’s standard stock, which is the part held against the shoulder. It frees the weapon to slide back and forth rapidly, harnessing the energy from the kickback shooters feel when the weapon fires.”

While bump stocks are not illegal, it has been illegal for private citizens to own automatic weapons since 1986.

Initially, the National Rifle Association announced it would support tighter restrictions on bump stocks but has since backed away from that position. In December, the Department of Justice and the Bureau of Alcohol, Tobacco and Firearms announced the agencies would look at regulations on bump stocks.

Senate Bill 51 “isn’t about new restrictions on the ability to purchase or own a firearm,” Merrifield said.  Automatic weapons are illegal without a permit nationwide, pointing out that a person just can’t walk into a sporting goods store and buy an M-16 machine gun.

“So why should the purchasing and installation of a kit that turns a legal weapon into an illegal weapon be legal?,” Merrifield said. “If we can make it more difficult, even for a moment, to turn a legal weapons into an illegal one, why not try? If even a speed bump of time is the difference between someone having second thoughts about causing harm…and a life is saved because of that pause, I believe it’s worth it, and 79 percent of Coloradans believe it’s worth it.”

Merrifield acknowledges getting his bill out of the Senate will be an uphill fight; the bill has already drawn opposition from the Senate’s Republican leadership. It’s been assigned to the Senate’s State, Veterans and Military Affairs Committee, which has been less than friendly with Merrifield bills in the past.

“I’m always optimistic…but if we can’t overcome the opposition, we need a strong, passionate conversation” about the issue, Merrifield said.

It’s not feel-good legislation, as some critics have charged. If that were true, Merrifield said, every law on the books is “feel-good law. But this bill will discourage people from attempting to buy bump stocks, and if it takes more time for a person to buy one, then we’ve done a good thing.”

The ban would apply to purchases online as well as in any brick-and-mortar store that sells them.

Despite the opposition from conservative Republicans, the momentum for banning bump stocks is alive and well outside of the state Capitol. The Denver City Council Monday night banned the sale of bump stocks; several other cities, including Columbia, South Carolina; and states, including Massachusetts and New Jersey, have already banned the devices. The Washington Post reported last week that at least 15 states are considering legislation to ban bump stocks.