"Today we're taking another step to fulfill a promise that many of us here made to the parents of the children of Sandy Hook Elementary School in Connecticut who suffered losses beyond comprehension," Senate Majority Leader Loretta Weinberg (D., Bergen), one of the bill's sponsors, said on the Senate floor Monday.
Assembly Democrats have long pushed for the magazine restriction, which gained traction this year when Senate President Stephen Sweeney (D., Gloucester) withdrew his opposition. He has said he changed his mind after meeting with the Sandy Hook parents.
Supporters of the legislation say forcing shooters to reload more frequently could give potential victims a chance to escape.
At legislative hearings this year, gun-rights advocates denounced the measure as a gun ban that would not deter criminals.
"The only people being punished by this legislation are law-abiding gun-owners," Sen. Mike Doherty (R., Warren) said on the Senate floor.
"Changing a magazine is about the simplest thing you can do," said Doherty, an Army veteran. "It takes a couple seconds."
Some Senate Democrats said they supported the bill, but lamented that it would ban antiques with fixed 15-round magazines owned by collectors and others.
For example, the bill would make illegal a rifle used by the U.S. cavalry during the Civil War, said Sen. Robert M. Gordon (D., Bergen). He voted in favor of the bill, but said he hoped the Legislature would consider an amendment exempting such guns.
The Senate passed the bill on a mostly party-line 22-17 vote.
Kevin Roberts, a spokesman for Gov. Christie, said the Republican governor would review the legislation if it reached his desk. Christie approved some gun-violence measures last year but vetoed others, such as a proposed ban on .50-caliber weapons.
Six states and the District of Columbia restrict magazine capacity to 10 rounds, and New Jersey's gun laws are already considered among the nation's toughest.
Also on Monday, the Senate voted, 21-17, along similar lines, to clarify the circumstances in which gun owners may transport their firearms.
Under current law, for example, firearm owners may take their gun to a repair shop or pistol club, among other places. In those situations, the gun owner may take only such "deviations as are reasonably necessary" while traveling.
The bill defines such deviations as "collecting and discharging certain passengers, purchasing fuel, using a restroom, contending with an emergency situation, and other reasonably necessary deviations of no more than 15 minutes in duration."
Republicans said they opposed the measure because it would allow judges to determine what is considered "reasonable."
It now heads to the Assembly for final legislative approval. The body's next voting session is scheduled for May 22.