US Air Force
Gunners Information File USAAF Manual No 20, B-17, B-24, B-25
This WWII-era bound edition of the US Army Air Force's Gunners Information File consists of several separate WWII-era manual publications combined into one hardback volume, dated May 1944. This manual is focused on those gun systems used in B-17, B-24, B-25, and B-26 bombers but is pre-B-29 Central Fire Control (so no B-29-specific content) .
The first section of describes the operation and maintenance of the .50 Caliber Browning M2 Aircraft Machine Gun. The second section describes sighting and sights. The third section describes various gun turrets and their operation.
This is not a 100% complete manual. Several pages are missing and others are slightly torn. Regardless, it is still packed with very interesting information. About 3/4 inch thick.