I have been told by someone who should know the pulse of EOPS thinking that the answer is yes if both possess the proper FID/LTC.
Others disagree and claim you need a dealer's license which is impossible to get for your home address. What I was told was in spite of some words in the first sentence of that law, it only applies to Dealers in MA (as wording further down in that law states).
Everything is illegal in MA. Start being a grown-up and let the small things go. He hands you the money, you hand him the ammunition. No complications, no SWAT raid, this isn't New York.