Not my firearm. Looking to purchase from a non-LTC (widow) so the sale has to go through an FFL. There is a revolver not on the roster that I would need to prove was in MA before '98. The seller can't find the original docs.
How old is the gun? Who made it? You might be better off just calling around and asking dealers about what they require for that kind of a transfer rather than assume that all have the same "proof" requirements.
-Mike