Leahy said the chiefs’ concerns with the bill include a provision that limits where gun owners may bring their weapons. He pointed out that the bill language doesn’t carve out off-duty police officers and state troopers, and argued that “criminals will not be deterred by these measures.”

The Massachusetts Chiefs of Police Association, which represents both municipal and campus police chiefs, conducted a poll Tuesday in which members unanimously voted against supporting the bill in its current form, Leahy said.

More than 160 people around the state, including Leahy, signed up to testify at the hearing, which lasted more than six hours.

Detractors including local gun groups and trainers, the National Rifle Association, and Gun Owners Action League called the bill unconstitutional, and worried about questions they claimed the legislation left unanswered.

Some critics also highlighted that the hearing was held just days after House leaders unveiled their revamped gun bill, giving the public a short window in which to read the large package and prepare a response.

Those who spoke in support of the bill included survivors of gun violence and medical professionals, who said further bolstering the state’s already-strong gun laws will make Massachusetts even safer.

Sean Horgan, a former Marine from Somerville, told lawmakers he supported the bill, especially its restrictions on assault-style weapons.

“All these weapons were designed for war,” he said. “There is no need for any of these weapons on our streets or in any town in Massachusetts. . . . For anyone who wants to get their hands on them, there is a Marines recruiting office right down the street from the State House.”

The revamped House bill sands off some of the edges from the earlier version in key provisions, including the restrictions on assault-style weapons and carrying guns in public places.

The new version would still require serialization of firearm parts, update the state’s assault weapons ban, and limit the ability to carry guns in certain spaces, but each of those provisions has been weakened from the original bill.

For example, the original bill would have banned certain assault-style weapons, drawing criticism from legal gun owners who felt that such a move would constitute “a government taking” of their lawfully owned property. The revised bill creates a so-called grandfather clause for people who legally owned such weapons before the law went into effect.

The original bill also would have banned people from carrying guns into public places without “explicit permission.” The revised bill would leave banning guns to the discretion of individual businesses, while keeping a ban in place for “sensitive spaces” like schools, government buildings, and polling places. The bill also makes clear that an individual must receive permission before bringing a gun into someone’s home.

Another major change involves how guns are serialized and registered, which aims to prevent the creation of unregistered “ghost guns.” The original bill would have required all gun barrels and receivers be serialized. But after hearing concerns from gun owners about “the efficacy and the practicality” of serializing the barrel of a long gun or a handgun, lawmakers revised the bill to require documentation on the gun’s frame instead, which lawmakers say is consistent with the federal requirements on firearms produced by licensed manufacturers.

The original bill was filed in June by Day, sparking loud pushback from gun groups and a protest from Senate Democrats, who fought with the House over which legislative committee should hold a public hearing on it.

The Senate has yet to file its own version of the bill, and an aide to Majority Leader Cindy Creem said this week it’s unclear when a bill would be drafted.

In a statement, a spokesperson for Senate President Karen E. Spilka said the Senate “will review this new House bill as well as the many other gun safety bills filed in the Senate and the House this session,” and that she aims to get a bill onto Governor Maura Healey’s desk this legislative session, which ends Jan. 7, 2025 (though the last day of formal session is July 31, 2024).

Samantha J. Gross can be reached at samantha.gross@globe.com. Follow her @samanthajgross.