Dunlap 1948: «The official rate during WWII was 450—575 rpm, but it was extremely rare to encounter an M2HB that exceeded 550 rpm.» Dunlap, Roy F. (1948). Ordnance Went Up Front: Some Observations and Experiences of a Sergeant of Ordnance, who served throughout World War II with the United States Army in Egypt, the Philippines and Japan, including way stations. A Samworth Book on Firearms. Plantersville, SC: Small-Arms Technical Publishing Co. OCLC6081851.
