Do I need a permit to purchase a gun in Massachusetts?
Low-capacity rifles or shotguns require a FID, as I understand it. If you want a high-capacity mag, you need at least Class B LTC (which will also allow you to get into handguns, as well). I’d just get the LTC. You might as well just apply for a Class A LTC, and not have to worry about what you are or are not allowed to buy. That’ll also cover your for concealed carry, if you live in a town where the sheriff doesn’t hate guns. Either way, you’ll have to take a firearm safety and training course. You might as well get your money’s worth. That way, if, in the next 6 years you decide that you’d like a pistol for home defense, you won’t have to re-apply (and wait another 2 months).