An emotional visit to Trenton by four families who lost children in the Newtown, Conn., shootings should have sharpened the debate over New Jersey legislation that would sensibly limit ammunition clips to 10 rounds.

As the Connecticut families told the New Jersey lawmakers last week, limiting the number of rounds in a high-capacity magazine can save lives, as evidenced by the fact that 11 students were able to escape when the Newtown shooter, Adam Lanza, paused to reload.

The 13th bullet fired by confessed shooter Jared Lee Loughner took the life of the 9-year-old granddaughter of former Phillies manager Dallas Green in the Arizona shooting that left six dead and critically wounded former U.S. Rep. Gabby Giffords.

That reality poses the gnawing question of whether little Christina-Taylor Green would have been killed had Loughner's gun carried fewer bullets.

It's little wonder then that the Newtown families view a limit on ammo clips as, in the words of the mother of one slain child, "one critical component that's very dear to our hearts."

So, like their counterparts in six states - and the nation as a whole, if Congress would approve President Obama's recommendation - New Jersey legislators easily could recalibrate the state's already progressive, 15-round limit.

Indeed, the promising package of gun-control measures put together by Assembly Majority Leader Louis D. Greenwald (D., Camden) includes the lower limit. Along with nearly two-dozen other gun-safety measures, the clip rules garnered Assembly approval in March.

Unfortunately, though, the magazine limit has run into opposition from Senate President Stephen Sweeney (D., Gloucester). Nor does Gov. Christie back the reform, saying he wants to focus instead on tougher penalties for straw buyers and gun traffickers.

Neither Sweeney nor Christie has made a convincing case for scuttling the Greenwald proposal. While Sweeney favors a number of other worthwhile gun-control measures - among them, banning ammunition sales over the Internet - his suggestion that the 10-round limit would inconvenience sportsmen is flimsy, at best.

Having to switch ammunition clips more frequently at the target range cannot be considered a serious justification for fighting the proposed 10-round limit.

With a needed change of heart, Sweeney could provide the right leadership to keep New Jersey in the forefront of fighting gun violence.