I have some good news for you. MA has always allowed sealing a record, but thanks to a 2018 law it is now also possible to expunge a record, which means MA will actually destroy the records. I suspect that FBI/NICS never deletes anything, but at least the new law helps at a state level.
For many people with an arrest but no conviction, MA never bothered to send the not-guilty/CWOF/dismissed disposition to the FBI, so convincing the state to send that along may be the better way to speed up one’s NICS checks. (I would be hesitant to expunge such a record before updating the disposition, because I could imagine getting in a situation where the feds don’t know if you were found guilty and the state no longer knows either.)
Depending on the conviction and the amount of time that has passed, you may be eligible to expunge your criminal record.
www.mass.gov