This manual prescribes the duties to be performed in the service of the piece by the personnel normally assigned to one howitzer section of the firing battery.
PM 4-175, Coast Artillery Field Manual, Antiaircraft Artillery Operation of Materiel and Employment of Personnel, Searchlight Units, is published for the information and guidance of all concerned.
"This 1942 manual is published for the information and guidance of personnel using the 20mm aircraft gun materiel M1 and M2 and contains technical information requried in the identification, use, and care of the materiel."