I remember the early days of Glidden's seminar to licensing officers/chiefs . . . before his PowerPoint seminars. He'd lay out guns and knives on a table and ask them which ones were illegal. Many LOs/chiefs pointed out that the ~8" Bowie knife was illegal . . . and Glidden would explain that MA has no restrictions on fixed-blade knives at the state level.I guess it all hinges on that word "automatic". Although ironically you could have a 3.5in blade with a ball bearing detent and no spring, be just as fast, and apparently, legal. So most cheap kershaw edc illegal, but if I carried my "ThATS a KNOIFE!" 560BW its well-legal, cuz no spring.. .
So you can count on LE ignorance wrt gun or knife laws and probable arrests with the "let the courts sort it out" attitude.