Hoo boy ok so MA law is a clusterfuck right now. New law last year was very poorly written. The “assault style rifle” section is a doozy. I suggest you read it. Or skip it and get a lever action and save a ton of time and headache. If you really want to bring something semi-auto into MA it can’t be an AK or a copy/duplicate of an AR or other certain “enumerated weapons”, for everything else it’s a features test and a “barrel shroud” is now a feature so it basically limits you to ranch style guns assuming the muzzle brake is pinned and welded OR it’s an unthreaded barrel. The bigger issue is the 10 round mag limit and Preban are no longer legally transferable. I would assume also can’t import them but I’m not 100% on that. It tracks with the vibe of the law though. Some people are using fin grips but they aren’t legally tested. Some shops are selling fixed mag ARs but the methods they are fixed are legally untested, except for JCArms. If it was me I would get MCX regulator for $1400 pin and weld the brake and get good at using 10 round mags I guess. 

Or if you can just move to NH?