Just looking at through legal means.
Clear as day really. Here’s the current law in force:
Section 131M: Assault weapon or large capacity feeding device not lawfully possessed on September 13, 1994; sale, transfer or possession; punishment
Section 131M. No person shall sell, offer for sale, transfer or possess an assault weapon or a large capacity feeding device that was not otherwise lawfully possessed on September 13, 1994. Whoever not being licensed under the provisions of section 122 violates the provisions of this section shall be punished, for a first offense, by a fine of not less than $1,000 nor more than $10,000 or by imprisonment for not less than one year nor more than ten years, or by both such fine and imprisonment, and for a second offense, by a fine of not less than $5,000 nor more than $15,000 or by imprisonment for not less than five years nor more than 15 years, or by both such fine and imprisonment.
The provisions of this section shall not apply to: (i) the possession by a law enforcement officer; or (ii) the possession by an individual who is retired from service with a law enforcement agency and is not otherwise prohibited from receiving such a weapon or feeding device from such agency upon retirement.
And the new law which will replace it on 10/23:
Section 131. The issuance and possession of a license to carry firearms shall be subject to the following conditions and restrictions: (a) A license shall entitle a holder thereof of a license to purchase, rent, lease, borrow, possess and carry firearms, including large capacity firearms and ammunition therefor. The license shall not entitle a holder thereof to transfer, possess or carry large capacity feeding devices or assault-style firearms unless such transfer, possession or carry is permitted under section 131M.
Section 131M. (a) No person shall possess, own, offer for sale, sell or otherwise transfer in the commonwealth or import into the commonwealth an assault-style firearm, or a large capacity feeding device.
(c) Subsection (a) shall not apply to large capacity feeding devices lawfully possessed on September 13, 1994 only if such possession is: (i) on private property owned or legally controlled by the person in possession of the large capacity feeding device; (ii) on private property that is not open to the public with the express permission of the property owner or the property owner’s authorized agent; (iii) while on the premises of a licensed firearms dealer or gunsmith for the purpose of lawful repair; (iv) at a licensed firing range or sports shooting competition venue; or (v) while traveling to and from these locations; provided, that the large capacity feeding device is stored unloaded and secured in a locked container in accordance with sections 131C and 131L. A person authorized under this subsection to possess a large capacity feeding device may only transfer the device to an heir or devisee, a person residing outside the commonwealth, or a licensed dealer.