501 CMR 20.09
Serialization of Firearms
(1) Serialization of metal firearms:
(a) The serial number shall be conspicuously engraved, cast, or otherwise permanently
embedded on the frame or receiver of the firearm.
(b) The serial number shall be placed in a manner that is not susceptible to being readily
obliterated, altered, or removed.
(c) The serial number shall be engraved, cast, or otherwise permanently embedded to a
depth of not less than .003 inches.
(d) The serial number shall be in a print size of not less than 1/16 inches.
(2) Serialization of non-metal firearms:
(a) The serial number shall be conspicuously engraved, cast, or otherwise permanently
embedded on a metal plate.
(b) The metal plate containing the serial number shall be permanently embedded in the
material of the frame or receiver of the firearm.