Ordnance Pamphlet 1439 is the U.S. Navy’s complete maintenance and parts manual for the twin 20-mm antiaircraft assemblies used aboard World War II warships. Prepared by the Pontiac Motor Division of General Motors Corporation for the Bureau of Ordnance, it covers the twin-mount 20-mm A.A. Gun Mounts Mark 20 and Mark 24 and their modifications, including description, lubrication, operation, stripping, assembly, and installation procedures. Also covered are the Shoulder Rests and Handle Bars Mk 8 Mod 0, Sight Adapter Equipment Mk 2 Mod 0, Machine Gun Mechanism Mk 4 Mod 1, and Magazine Mk 5 Mod 0. The pamphlet concludes with a detailed illustrated parts list, numerical index, and distribution diagrams. Note: This document does NOT contain a page 122.
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