There are several drug possession charges under MGL c. 94C s. 34 as well as possession with intent of class D or E (MGL c. 94C Ss. 32c(a), 32C(b), 32D(a), and 32D(b)) that could still be Mass prohibitive but not federally prohibitive, once the federal prohibition of firearm possession by persons who are the unlawful user of/ addicted to controlled substances is remedied.
Remember, also, that there are people who may have convictions from states other than Massachusetts that would be prohibitive under Massachusetts law but not under federal law. For example, in 2015, Connecticut made possession of many types of controlled substances a class A misdemeanor. There are also numerous crimes of violence from other states that are misdemeanors punishable by less than 2 years imprisonment. And let's not forget the people with out of state, misdemeanor weapons violations....
Lastly, there are also individuals whom may have been denied an LTC or FID on more subjective grounds- who are not inherently disqualified but whom an issuing authority decided was not suitable for some reason.