Gun owners in Massachusetts are being warned if they own bump stocks, they have two weeks to get rid of them.

The Massachusetts legislature voted last year to ban them and Feb. 1 is the deadline to comply or face criminal charges.

"This is not a joke," said Jim Wallace, executive director of the Gun Owners Action League. "A violation of this new law is up to life in prison."

Wallace says many bump stock owners may not be familiar with the new law, and a warning from Massachusetts state officials to gun owners — despite being dated Dec. 18 — only went out Friday, more than a month later.

"Oh, it should have been sent out a long time ago," said Wallace.

Bump stocks made international headlines when a gunman opened fire from a hotel room in Las Vegas back in October. The shooter, Stephen Paddock, used bump stocks to increase the rate of fire.

Lawmakers in Massachusetts then voted to ban them.

"Gun owners are facing a very important deadline coming up, and the state has not done their due diligence in notifying gun owners," said Wallace.

It's unclear why the letter just went out Friday. It's now being mailed to all gun owners to explain the consequences of not surrendering bump stocks.

There are no exceptions.

State Rep. David Linsky, who was behind the bump stock legislation, said

"The ban ... was extremely well publicized," said Massachusetts Rep. David Linsky, who was behind the legislation. "People who still own them are well aware of the changes in the law."

Bump stock owners are supposed to call their local police department or Massachusetts State Police to make arrangements to have them destroyed.