An estimated 10,000 "copycat" assault weapons were sold in Massachusetts during 2015, according to the attorney general's office, which announced a crackdown effort on Wednesday.

Joined by anti-violence advocates and members of law enforcement, Attorney General Maura Healey said she issued a notice to all Massachusetts gun sellers and manufacturers warning that her office is stepping up enforcement of the state's assault weapon ban.

The notice clarifies what constitutes a "copy" or "duplicate" weapon that would also be prohibited under the ban.

Attorney General Maura Healey, joined by activists and law enforcement, announced on Wednesday heightened enforcement of the state's assault weapon ban. [Photo: Katie Lannan/SHNS]

"My office's actions today will give us the full protections of the state's assault weapons ban to do what it was intended to do and not leave it to the gun manufacturers' self appointed interpretation," Healey said. "The gun industry doesn't get to decide what's compliant. We do."

In effect since 1998, the Massachusetts law mirrors a federal assault weapons ban that expired in 2004, prohibiting the sale of specific name-brand weapons and any copies or duplicates.

Healey said gun manufacturers make minor tweaks to weapons -- such as removing the flash suppressor -- and then market them as "Massachusetts compliant" versions. Such changes do not "address the lethality of the weapons," the attorney general said.

A gun qualifies as a forbidden copycat if it is "substantially similar in construction and configuration" to one of the banned guns or has interchangeable key parts, according to the enforcement notice.

"It seems like the gun industry has found a way around our laws, and the intent of the law is not being recognized," Rep. Lori Ehrlich, a Marblehead Democrat, told the News Service after Healey's announcement.

"The Legislature and the governor together make laws, and sometimes we can't anticipate workarounds, so I appreciate that the attorney general is stepping up," Ehrlich said.

Speakers at the event said Healey's actions did not represent a new law or set of regulations but heightened enforcement of an existing statute.

Jim Wallace, the executive director of the Gun Owners Action League of Massachusetts, disputed that idea.

"It's pretty scary that someone can come in and unilaterally change the rules overnight," Wallace told the News Service. "The firearm retailers, under the enforcement of the Executive Office of Public Safety, have been operating under a set of rules for 18 years, so to come in and unilaterally say 'We don't agree with this, this is what we say' -- of course that's a change. How can that not be a change?"

Healey said she will not seek to enforce the ban against consumers who already own the copycat guns, if the weapons were purchased before Wednesday.

The state's 350 gun sellers would not be permitted to sell their current stock of such guns to Massachusetts buyers but may "transfer them out-of-state to jurisdictions where sales of these weapons are legal," according to the attorney general's office.

"If we reach one manufacturer from pumping these guns out, I think it's worth it," Boston Police Commissioner William Evans said.

Asked by a reporter after the press conference, Evans said he had previously been under the impression that the guns were compliant with state law.

"You know, honestly, I was. I think, it's alarming to find out that since Orlando, there's been a big rush to buy these," he said, referencing the June 12 mass shooting at a Florida nightclub that prompted renewed calls for tighter gun laws. "There's no need for these guns, especially in a city where they can cause so much harm."