I was directed to this thread by another guy in this forum because there is some confusion about what the legal capacity for semi-automatic shotguns is in MA.
Most people think you can have a 7 round semi-automatic shotgun as long as it doesn't have a pistol grip, but they are going by the Assault Weapon definition only. Here is an example from this thread.
I used to think the same thing until I inquired of a very well know FFL in Littleton (one of the legit ones that does Glocks and ARs) and he told me that, "It has NEVER been legal to have a semi auto shotgun in MA with over 5 round capacity." He also said if you have a semi-auto shotgun with more than 5 rounds it's a felony and if it also has a pistol grip it's 2 felonies.
The reason why has nothing to do with the AW law, it is the "Large capacity weapon" law that makes it illegal.
Here is the current wording after mid-2024
'Large capacity weapon'', any firearm, rifle or shotgun: (i) that is semiautomatic with a fixed large capacity feeding device; (ii) that is semiautomatic and capable of accepting, or readily modifiable to accept, any detachable large capacity feeding device; (iii) that employs a rotating cylinder capable of accepting more than ten rounds of ammunition in a rifle or firearm and more than five shotgun shells in the case of a shotgun or firearm; or (iv) that is an assault weapon.
Here is the law prior to mid-2024. I underlined the words relevant to semi-auto shotguns. The words in bold show why a pump shotgun CAN have more than 5 rounds.
“Large capacity weapon”, any firearm, rifle or shotgun: (i) that is semiautomatic with a fixed large capacity feeding device; (ii) that is semiautomatic and capable of accepting, or readily modifiable to accept, any detachable large capacity feeding device; (iii) that employs a rotating cylinder capable of accepting more than ten rounds of ammunition in a rifle or firearm and more than five shotgun shells in the case of a shotgun or firearm; or (iv) that is an assault weapon. The term “large capacity weapon” shall be a secondary designation and shall apply to a weapon in addition to its primary designation as a firearm, rifle or shotgun and shall not include: (i) any weapon that was manufactured in or prior to the year 1899; (ii) any weapon that operates by manual bolt, pump, lever or slide action; (iii) any weapon that is a single-shot weapon; (iv) any weapon that has been modified so as to render it permanently inoperable or otherwise rendered permanently unable to be designated a large capacity weapon; or (v) any weapon that is an antique or relic, theatrical prop or other weapon that is not capable of firing a projectile and which is not intended for use as a functional weapon and cannot be readily modified through a combination of available parts into an operable large capacity weapon.