N.J. Stat. Ann. § 23:4-35

The board, protector and wardens may, when they suspect the concealment of guns of the kind mentioned in section 23:4-31 of this title by an unnaturalized, foreign-born person, apply to a justice of the peace in this state, who, upon receipt of proof made by affidavit of the probable cause for believing in the concealment, shall issue a search warrant, and cause a search to be made in any place. In execution of the warrant, the officer may, after demand and refusal, cause any building, room, inclosure or car to be broken open and entered, and any closet, chest, locker, box, trunk, crate, basket, package or receptacle to be opened and its contents examined.