Declaring that their law bans the sale of any rifle that has interchangeable parts with any other rifle on their 'banned' list, by a stroke of a pen they have made illegal the sale of whole categories of rifles designed to be compliant with their state laws.
It's my understanding that (unlike handguns) you can buy a rifle while traveling in a different state than the one in which you reside, as long as you buy from a licensed gun dealer. (If you're worried about government records, you can then sell that rifle to someone in your own state in trade for another rifle they own -- which they can have purchased out of state from a licensed gun dealer.)
Massachusetts isn't that big of a state. Working around its restrictions on the right to keep and bear arms should be doable for most.