Who may qualify as a certifying official on an ATF Form 1 or ATF Form 4 for the making or transfer of an NFA firearm?

As provided by regulations, certifications by the local chief of police, sheriff of the county, head of the State police, or State or local district attorney or prosecutor are acceptable. The regulations also provide that certifications of other officials are appropriate if found in a particular case to be acceptable to the Director.  Examples of other officials who have been accepted in specific situations include State attorneys general and judges of State courts having authority to conduct jury trials in felony cases.

Effective July 13, 2016, the final rule “Machineguns, Destructive Devices and Certain Other Firearms; Background Checks for Responsible Persons of a Trust or Legal Entity With Respect to Making or Transferring a Firearm” amends the regulations to eliminate the requirement for a certification signed by a CLEO and instead adds a CLEO notification requirement.  Prior to the submission of an ATF Form 1 or ATF Form 4 to the Director, all applicants/transferees and responsible persons shall forward a completed copy of ATF Form 1 or 4, or a completed copy of Form 5320.23, respectively, to the chief law enforcement officer of the locality in which the applicant/transferee or responsible person is located.  The chief law enforcement officer is the local chief of police, county sheriff, head of the State police, State or local district attorney or prosecutor.  If the applicant/transferee is not a licensed manufacturer, importer, or dealer qualified under this part and is a partnership, company, association, or corporation, for purposes of this section, it is considered located at its principal office or principal place of business; if the applicant/transferee is not a licensed manufacturer, importer, or dealer qualified under this part and is a trust, for purposes of this section, it is considered located at the primary location at which the firearm will be maintained.

Source ATF: https://www.atf.gov/firearms/qa/who-may-qualify-certifying-official-atf-form-1-or-atf-form-4-making-or-transfer-nfa