When I had an 07/SOT in MA I had no problem with manufacturing and transferring on my license, but I never tried anything as an individual, because why poke the bear. That is a really good question, as the MGL says "Whoever, except as provided by law," and only points to the MGLs on machineguns. I wouldn't expect to make any friends with that loophole, should it exist...
I know of one other manufacturer in MA, years back, who decided to remanufacture factory weapons into his own "shockwave" style Firearms. After consulting with the ATF, he was given an approval letter to take Shotguns AND Firearms (provided he logged the change in AFMER status for shotguns) and marked the receiver of either with his own information as the new "manufacturer". The problem became that while the ATF has no issue with appropriately licensed manufacturers changing AFMER status (even in ways that non-FFLs cannot i.e. rifle to pistol), MA has that stupid provision about being made out of a shotgun... and considers 18" pistol-grip-only "firearms" to be shotguns as well. A few were made, none were sold here, the state had no problem with them on an FFLs books but did not want them transferred to LTC holders.
In the end, a virgin receiver would have been fine, but what would it be called on an FA10? Probably a pistol... but it's off roster. So now you get into selling receivers separately...