c. 265, § 58
Possession of deceptive firearm device during commission of violent crime; penalty
Official text prohibited actmental stateif conditionpenaltylegal term
Any person who is in possession of a deceptive firearm device as defined in section 121 of chapter 140 during the commission of a violent crime as defined in said section 121 of said chapter 140 shall be deemed to be armed and shall be punishable by penalties set forth in this chapter.
Simplified explanation
Possessing a deceptive firearm device while committing a violent crime means the person is treated as armed and faces the armed-crime penalties set elsewhere in chapter 265.