Chippy, I believe you are mistaken.
It is absolutely legal to use any necessary force to protect oneself, family, and personal possession from any threat, given they have sufficient means to believe that another individuals intends to threaten the personal safety of themselves, their family members, or their personal property, in the state of Massachusetts.
Massachusetts just makes it difficult to own said means of protection, because they feel if they provided their citizens with anything more menacing than a spork, every law-abiding citizen would turn into raging psychopathic serial killers and go on a rampage of murder and pillage. Despite the fact that the majority of all homicides committed in Massachusetts are committed using illegally-acquired weaponry.
The State of Massachusetts also prefers to ignore the fact that a similar ban of certain types of citizen-owned firearms in England in 1997, {specifically air pistols}, which results in an 300 percent rise in annual homicides and armed burglary crimes committed within the city limits. This is most likely due to the fact that law-abiding citizens were no longer able to protect themselves against these criminals, while the ability for criminals to obtain illegally-acquired firearms was not affected. If anything, the black market for illegally-acquired firearms was strengthened by this ban by creating a clientele of previously law-abiding citizens whom were willing to obtain illegally-acquired firearms in order to protect their personal safety, as well as the safety of their family members.
Massachusetts officials also prefer to forget the Second Amendment to the United States Constitution which states, and I quote, "the right of the people to keep and bear arms shall not be infringed."
If we cannot count on our government leaders to protect our most basic rights as defined in the United States Constitution, which defines the very ideals in which this country was based on, then it is our right and our duty as citizens to take action to remove these officials from office, a right specifically stated in The Declaration of Independence. "But when a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Government, and to provide new Guards for their future security."