... I can come up with no law that requires a non dealer to check their LTC or any of your other terms. If someone is aware of one, please point us all at it.
In the case of a LCFD, the transferee must have an LTC:
MGL 140-129C said:Nothing in this section shall permit the sale or transfer of any large capacity rifle or shotgun or large capacity feeding device therefor to any person not in possession of a Class A or Class B license to carry firearms issued under section 131, or of any large capacity firearm or large capacity feeding device therefor to any person not in possession of a Class A license to carry firearms issued under section 131.
https://malegislature.gov/Laws/GeneralLaws/PartI/TitleXX/Chapter140/Section129C
If the transferee is sans LTC, the penalty for the transferor is 2.5-10 years imprisonment:
MGL 269-10F said:(a) Any person who sells, keeps for sale, or offers or exposes for sale, gives or otherwise transfers any large capacity weapon or large capacity feeding device, both as defined in section 121 of chapter 140, to a person 18 years of age or over, except as permitted under this section or chapter 140, shall be punished by imprisonment in a state prison for not less than two and one-half years nor more than ten years.
https://malegislature.gov/Laws/GeneralLaws/PartIV/TitleI/Chapter269/Section10F
Arguably, a non-large capacity feeding device does not require a license to possess, but I digress.