7/25/18 - This is an original copy of THE MACHINE GUN: Design Analysis of Automatic Firing Mechanisms and Related Components by George M. Chinn: Lieutenant Colonel, USMCR. This is volume IV only (parts X and XI). Prepared for the Bureau of Ordnance Department of the Navy. Published in 1955 and covers blowback systems, recoil and gas operation, and rotary chamber mechanisms (part X). Part XI has schematic illustrations of representative mechanisms. Covering feed systems, locking systems, and various automatic gun parts. Extensive research and coverage on the subject. The pages are excellent (638 total). Hardcover is also in excellent condition.