HARRISBURG - The House yesterday rejected a measure aimed at curbing illegal handgun trafficking, the first substantive gun restriction considered by the full chamber in more than a decade.

By a vote of 128-75 the House defeated an amendment - attached to a separate gun crime bill - that would have made it mandatory to report lost and stolen handguns.

The amendment won overwhelming support from Philadelphia-area lawmakers, where polls show majority support for the reporting requirement. House Speaker Dennis O'Brien, a Republican, was the only representative from Philadelphia to vote against the measure.

O'Brien said he could not support what he called a "flawed bill" and felt it could have "unintended consequences" for legitimate crime victims, such as felony charges for not reporting multiple missing weapons. "It's a difficult vote to explain why you're not for it, but the deficiencies were glaring."

Gun-control proponents hailed the vote itself as a historic achievement for opening floor debate on gun violence and forcing lawmakers to take a formal position on controversial legislation.

The defeat came despite impassioned pleas from Philadelphia- and Pittsburgh-area lawmakers who argued that the legislation was critically needed to control the flow of illegal weapons and protect the innocent caught in the crossfire.

"This is a defining moment in this state . . . and to the families of the 400 people gunned down in Philadelphia last year," said Rep. Curtis Thomas (D., Phila.). "The urgency of now requires that we respond to people across Pennsylvania that have said we need to do something now."

But the final vote reflected the dominant pro-gun ideology in a state where divisions over gun control run largely along geographic rather than party lines.

Pro-gun lawmakers from both parties argued that police should enforce existing laws and said that this new restriction would make criminals out of law-abiding citizens.

"All it does is criminalize the innocent man or the victim . . . and legislates morality and values," said Rep. John Pallone (D., Westmoreland). "If something happens a lawful gun owner . . . would report it to proper authorities."

The National Rifle Association, with 250,000 members in Pennsylvania, fought vigorously against the bill right up to the vote.

Debate on the gun-control legislation, which has been bottled up in committee for more than a year, began late yesterday afternoon.

Rep. David Levdansky (D., Allegheny), the amendment's sponsor and an avid hunter, argued that most sportsmen do not have an issue with reasonable handgun restrictions.

But opponents cited lax enforcement and light sentencing for gun-related crime. Rep. Scott Perry (R., York) blamed "liberal judges" for letting criminals out of jail early.

"We need crime control, not gun control," he said.

The amendment would have made it mandatory for owners to report missing handguns within three days of discovering that they were gone. Failing to do so could have resulted in a penalty of a summary charge for the first offense and a felony for the third offense.

Seven other states and the District of Columbia have similar laws.

The amendment was propelled to the floor with the support of Gov. Rendell, mayors across the state, law enforcement and district attorneys.

They said it would close loopholes in existing laws that allowed so-called straw purchases of handguns - in which people without criminal records buy guns for felons.

The defeated proposal was an amendment to a bill that would increase criminal penalties for possessing guns with altered or obliterated serial numbers.

Supporters said they would continue to push the original mandatory reporting legislation, which remains under consideration by the House Judiciary Committee.

"We find it disappointing that even the most commonsense crime-control legislation can't muster a majority in the House at this point," Rendell spokesman Chuck Ardo said. "But we will continue working with our allies to build support for another day."

Contact staff writer Amy Worden at 717-783-2584 or aworden@phillynews.com.