This description, found in an old online auction, says:
Oswald has made notes and edits in pencil in "The M1 Rifle" chapter, the only handwritten notes in the book. On page 171, the first page of the chapter, the listing of "Average rate of aimed fire per minute" is "30 rounds." Oswald has crossed out "30" and written "16-24."
In trying to figure out why he would make that notation, I have the following suggestion based on my conjecture. The reduced rate is more in line with a bolt action rifle like Oswald’s Carcano. Marina has reportedly said that LHO practiced aiming and dry firing his rifle on the porch in New Orleans. Perhaps that rate is what he found he could do with the Carcano? Just a thought. What do you think?
Oswald's signed Guidebook for Marines with corrections by him in the "Rifle" chapter plus documents related to Oswald's 1963 arrest in New Orleans
(1) Lee Harvey Oswald Guidebook for Marines Signed "PVT. LEE H. OSWALD/NO. 1653230" in light pencil in block letters on title page, 476 pages, 6.5" x 8.25". Published by the Leatherneck Association, Inc. Washington, D.C. Fifth Revised Edition, First Printing, January 1, 1956. From the Preface: "This fifth revision of the original Guidebook For Marines is the result of a combined effort by Headquarters, U.S. Marine Corps, Marine Corps Schools and Leatherneck Magazine..." Stamped in the upper margin on the title page, lightly on page 80, and on page 91, is "L H. OSWALD." Worn, heavily creased fabrikoid covers, copiously illustrated with photographs and diagrams. Torn spine with front cover and spine partially separated from the text. The first 90 pages, including the title page, are dog-eared in the lower right, decreasing in degree, page by page. The last 120 pages, 353-476, are dog-eared in the upper right, increasing in degree, page by page. Some other pages have tears at the corners or are dog-eared to a lesser extent. The "53" of Oswald's Service Serial Number has been effaced. Of special interest is Chapter15, "The M1 Rifle."
Oswald has made notes and edits in pencil in "The M1 Rifle" chapter, the only handwritten notes in the book. On page 171, the first page of the chapter, the listing of "Average rate of aimed fire per minute" is "30 rounds." Oswald has crossed out "30" and written "16-24." [The Warren Report concluded that "the three shots were fired in a time period ranging from approximately 4.8 to in excess of 7 seconds"]. On page 180, he's crossed out the word "Movement" in "Movement of the operating rod" replacing it with "action." On page 181, Oswald replaced "Action of the follower" with "(feeding)" and underlined the first word in "Termination of rearward movement." On page 189, the last page of the chapter, in the subchapter headed "Sight Setting," he has underlined the 15 words (here in quotes) explaining the elevating and windage knob clicks on the rifle, with each click representing "1 minute of angle or approximately 1 inch on the target for each 100 yards" of range. [The Warren Report stated "The President was 265.3 feet from the rifle in the sixth-floor window and at that position the approximate angle of declination was 15°21'.331."]