I always read this about the time it takes to train an infantryman to be effective out to the range that a full power round allows. Prior to the change over to the range limited 5.56 EVERY Marine and U.S. Army recruit had to qualify out to at least 600 yards.
No, the change to shorter-range, more "practical" rifle marksmanship began immediately after World War II and was a result of the experiences in that war.
Here's a 1954 paper from Fort Benning advocating a very familiar course of fire that does not exceed 350 yards in distance.
My cousin, in the late 1960s was on his Army divisional rifle team, competition included 1,000 yard targets engaged with M-14s with IRON SIGHTS.
Rifle marksmanship teams STILL compete out to 1,000 yards, and do so with AR-15s.
The Marines and the Army routinely trained troops out past 600 yards until they wound up with a caliber that simply can't manage that sort of range.
Nope.
After WWI, the US Army had a variety of qualification courses. Course A went out to 600 yards, while Course D, for example, went to only 200 yards. In 1940, they standardized on Course B, which went to 500 yards, for riflemen, and Course C for everyone else with an M1. Then the Army cut it to 328 yards (300 meters) in light of experience in WWII and Korea.
The Army used to require troops to qualify on a skirmish course at ranges to 600 yards with a .30-40 Krag.
Yeah, they also didn't have any machine guns or infantry mortars back then, either.
Even today the Marines require EVERY RECRUIT to qualify out to 500 yards (although it is only firing from the prone position these days) using the 5.56mm.
Hah, yeah they do. I asked a Marine marksmanship SME what he thought the maximum effective range of a US Marine grunt was, once. His answer? "No more than 200 meters!"
The Army might have decided that it was too hard to train up troops, no idea why, but during WW II the managed to train several million troops out past 500 yards (you had to qualify out to 300 with the M-1 Carbine). I somehow doubt that the average WW II draftee, many of whom were barely able to get through the physical due to malnutrition during the Depression (shocking number of 4Fs from that cause early in the war) were better prepared to qualify at 500+ yards than those from Vietnam or today's volunteer force.
The Army decided it was unnecessary to train troops to qualify out to 500 yards, in light of their experience in WWII. Keep in mind, many of those who didn't qualify got waivers. What was the point of turning them away in a time of war? In fact, shortages got so bad that the War Department weighed in in January 1945: "the present exceedingly large over-all demands for infantry replacements can be satisfied even in part only by use of men who are not fully qualified physically for infantry duty and by waiver of minor training deficiencies",
THE PROCUREMENT AND TRAINING OF GROUND COMBAT TROOPS, page 221.