Republicans spent hours arguing that the limit violates Second Amendment rights. They also cited a Colorado gun manufacturer that has threatened to leave Colorado if the measure becomes law. The bill was amended to exempt that company, but Republicans still argued against the measure.
"We are not safer by limiting the constitutional rights of law-abiding firearm owners," said Republican Rep. Frank McNulty.
A few Democrats appeared to agree Friday, though an exact vote count won't be known until recorded votes are taken Monday. GOP leaders were hoping gun activists would spend the weekend pressuring rural Democrats like Rep. Ed Vigil of southern Colorado, the only Democrat who argued Friday against any ammunition limit.
"We should be going down the path of making mental health available to people who really need it," Vigil argued.
The gun debate was at times emotional and pointed. One gun lobbyist was asked to leave the Capitol after a heated exchange off the floor with a Republican lawmaker who said the lobbyist was falsely accusing her of considering voting for the gun-control measures. The gallery was at times packed with gun-rights activists.
Democratic Gov. John Hickenlooper has said favors some of the gun-control measures. Hickenlooper supports expanded background checks and indicated Thursday that he could support a potential amendment on magazine sizes, if the restriction was between 15 and 20 rounds.
He also said he thinks gun purchasers should pay for their background checks, but he had not made up his mind yet about the ban on concealed firearms on colleges.
All of the proposals still need to be considered by Democrat-controlled Senate.
Democrats in the Legislature said the time is right to limit gun access and magazine sizes to prevent more shootings.
"This is about kids who have been shot, over and over and over again," said Democratic Rep. Crisanta Duran said. "I am tired of seeing kids die, year after year, after year, after year."
Find Ivan Moreno at http://twitter.com/IvanJourno and Kristen Wyatt at http://www.twitter.com/APkristenwyatt.