Here is just one link to what appears to be a good site regarding firearms laws in your state. As Plan "A" I respectfully suggest obeying the law whether you agree with it or not.
http://www.mass.gov/dfwele/dfw/educa...d_gun_laws.htm
Here in NY, which has the most restrictive laws of any state, (with the possible exception of California), the circumstances you describe would require the following:
Surrender the handgun to a local police agency for safekeeping.
Apply for a "certificate of non-destruct."
The police run the firearm's serial number. When it comes back "no hit" (as I presume that it will) the licensing authority register's the weapon to your permit and off you go with a legal firearm being transported legally which you can use in public and show to your friends and family. Since you have no permit at the moment, you would of course have to obtain the requisite authority to be in posession of a handgun before the Luger was returned to you. Obvioulsy, before you give the gun to the police, you would want to coat it liberally with a good protective gun oil, or maybe some heavier protectant such as RIG (my favotie for long term storage.)
My point is that even in New York, your gun would not simply be taken away and destroyed. I SUSPECT (the key word here is "suspect," that Mass would have a similar procedure. The best way to find out is to contact the agency which issues firearms cards and ask.
Plan "B" is to become a criminal and violate your state's laws. Following this plan will prevent you from ever shooting the Luger in public without fear of arrest, prevent you from lawfully buying ammunition since you need a firearms card in Mass. to buy ammunition (of course you could cross state lines to buy ammunition, thus committing another crime) , and prevent you from ever showing your family heirloom to anyone who might one day get angry with you and turn you into the police.
Personally, I would go with plan "A".
Regards,
Doug