I have no personal knowledge of this topic, but I took a quick tour of the web searching for facts that may help you. Two things I found: The MA Historical Society's page states the the Bucks did not participate in the Battle of Groton (Groton Heights?). There was some name confusion with another person that caused this myth to propagate.
The other interesting fact is that apparently many members of the Bucks were from Hartford or elsewhere in CT. That's because at the time CT did not allow blacks to serve in the militia, so blacks who wanted to do so joined the Bucks in MA. I didn't have time to verify the information on the page at the link below. Since the information is not annotated, you may want to check further before accepting it as absolutely true, since anyone can put anything they want on a website.
To Join the Company of Military Historians click here