Testifying before a divided U.S. Senate Judiciary Committee, Neil Heslin, whose son Jesse Lewis was murdered in the December 14 shootings that killed 20 children and six adults, joined an emergency room doctor in recalling the damage done by such a weapon. Heslin held up a picture of his son during his testimony and at times his voice choked with emotion.

"I'm not here for sympathy. I'm here to speak up for my son," Heslin said. Lewis, hit twice in the head, "lost his life ... because of a gun that nobody needs and nobody should have a right to have," Heslin said.

Dr William Begg told the panel that each child who was killed at Sandy Hook Elementary School in Newtown, Connecticut, had three to 11 bullet wounds.

"The gun legislation that you are considering will make a difference," Begg said. "It could prevent future tragedies like Newtown."

The Democrat-led committee is expected to approve, on a party line vote of 10-8, a bill to outlaw military-style semi-automatic rifles and magazines with more than 10 bullets.

But the measure, one of four gun-control bills inspired by Sandy Hook, is likely to face a bipartisan roadblock on the floor of the Democrat-led Senate.