Over the objections of hundreds of gun rights supporters, a Colorado House Committee passed a bill requiring background checks for private gun sales Tuesday afternoon and a measure that would ban high-capacity ammunition magazines late Tuesday night.

Passage in each case was split along party lines, with seven Democrats voting yes and four Republicans no.

The vote on the high-capacity magazine came after Democrats on the House Judiciary Committee voted to amend a bill that would ban high-capacity ammunition magazines of more than 10-rounds to increase that limit to 15 rounds.

State Rep. Mike McLachlan, D-Durango, who sits on the committee, said he offered the amendment to allow citizens to protect themselves.

“Fifteen is a reasonable number and this is what I’m going to ask in my amendment,” McLachlan said.

The vote on the amendment came after a long recess in a day that’s seen several hours of impassioned testimony from proponents and opponents of tougher gun legislation.

State Rep. Rhonda Fields, D-Aurora, the sponsored the legislation, said she was against the amendment.

“It’s not what I want and not what I had in mind,” Fields said.

Fields, who also sponsored the background checks, said a major reason for her presenting the bill that bans high-capacity magazines of more than 10 rounds is because of last July’s Aurora theater shooting.

“Many of those people are critically injured for life because of their wounds,” Fields said. “These high-capacity magazines allow a gun to fire large amounts of bullets to kill people as fast as possible.”

Many of the hundreds that packed the Capitol earlier on Tuesday departed as the testimony on the high-capacity ammunition bill convened.

Arapahoe County Coroner Michael Dobersen, whose office received the bodies of victims killed in the Aurora theater shooting , said in testimony that firearms with these appendages produce some of the most gruesome wounds he’s ever seen.

“These rounds have a devastating effect on the body,” Dobersen said. “Can you imagine seeing multiple wounds from this? Even one bullet wound is devastating, but those from high-capacity magazines are especially bad.”

State Rep. Mike McLachlan, D-Durango, who sits on the committee, said he will offer the amendment and says that number allows citizens to protect themselves.

“Fifteen is a reasonable number and this is what I’m going to ask in my amendment,” McLachlan said.

In its current form, a person who already owns a magazine that could hold more than 10 rounds or five shells when the bill becomes effective July 1 could still legally own it but would have to maintain continuous possession of it .

The first bill before the House Judiciary Committee on Tuesday, House Bill 1229, would require a background check for any transfer of a firearm except in certain instances such as those involving antique firearms or gifts between immediate family members. Critics of the bill say it is unenforceable without gun registration.

Rep. Daniel Kagan, D-Cherry Hills Village, asked the hundreds of people crammed into the Old Supreme Court Chambers at the Capitol to please refrain from applause or other public displays.

“This is a policy-making procedure,” Kagan said. “It’s not a political rally.”

But that admonition was quickly violated when Rep. Beth McCann, D-Denver, a co-sponsor of the background checks bill, said “reasonable restrictions” could be placed on Second Amendment rights.

Many in the crowd jeered, prompting Kagan to bang his gavel and ask that the hearing not be turned into a “theatrical” event.

Fields pointed to a Denver Post poll done in January that showed 83 percent of Coloradans supported background checks for all gun sales.

While purchasers must undergo a background check when buying from a gun dealer, private sales between individuals do not have this requirement. Fields said only 40 percent of all gun sales undergo background checks, and pointed to a survey of prison inmates in which 80 percent who used handguns in a crime said they acquired them through private sales.

“The private sale loophole is just a way for criminals to skirt around our current background check,” Fields said.

Testimony also came from David Chipman, a former agent with the U.S. Bureau of Alcohol, Tobacco and Firearms who helped with rescue efforts in the 9/11 and Oklahoma City bombing events.

“Background checks work,” Chipman said. “They will strengthen our shield.”

Testimony also included the personal experiences of several victims of gun violence, including Karina Vargas, 18, who was a student at Aurora Central High School in 2010 when she was paralyzed from the waist down after being hit by a stray bullet during a gang altercation.

“I feel like with speaking out, it might make someone think twice before they try and buy a gun if they have to have a background check,” Vargas said following her testimony. “Maybe if the guy who shot me had to have a background check, then he would not have had a gun.”

But there were far more opponents in the hearing room than supporters of the bill.

They included Daniel Carey, a state lobbyist for the National Rifle Association, who said the bill wouldn’t stop any illegal gun sales but would put an unjust burden on law-abiding citizens.

“Criminals don’t abide by the law,” Carey said. “That’s what makes them criminals.”

Supporters of the bill pointed out that the NRA had once supported the universal checks.

Opponents who testified against the bill included those who blamed gun violence on video games and movies to psychiatric medications.

James Winchester, former vice president of the Colorado State Shooting Association and who helped write the original law setting up background checks, also testified against the bill. He said the Colorado Bureau of Investigation is not honoring the current three-day requirement in law for the checks.

The committee passed the bill on a 7-4, party line vote.

Kagan set a time limit of two hours for proponents and opponents of both bills, theoretically limiting the hearing to eight hours. But some witnesses early on got to speak for much longer, and some observers thought the hearing could stretch on much longer.

Tim Hoover: 303-954-1626, thoover@denverpost.com or twitter.com/timhoover