What Emeric wrote is exactly what U.S. sources (like Hatcher's Notebook p. 23ff) say. 

What is your view why the M1 was dropped and the M1906 (under the new name M2) re-introduced? 

graylion said:

EmericD said: They reverted to the Mle1906 shape for the .30 M2 excatly because the M1 had too much range, and not enough drag... Huh???

I've already dealt with this in posts 49 and 51 in this thread.

The "complete" story as told by Col. Hatcher:

At this time we had on hand about two billion of the war-time .30-'06 cartridges, and as ammunition is perishable, the policy was to use up the oldest ammunition first, keeping the newer for war reserve.
Thus the shooters on Army, National Guard and Civilian rifle ranges had to use the old war time stuff, while wishing for the happy day to come when they could get some of the good new ammunition [the M1] to use.
Finally about 1936 that wished-for day arrived, and with it trouble of an unexpected sort. The new ammunition had so much longer range and carrying power that it began to shout beyond the
previous danger zones of the existing ranges. The National Guard Bureau then requested the War Department to make up some ammunition like the old 1906, to use on the restricted ranges, and the order was given to make up 10,000,000 rounds of it.
This short range ammunition was made as much like the 1906 as possible. It had a 150 grain flat base bullet, but the jacket was of course made of gilding metal instead of the old cupro-nickel. It was,
however, colored to look like the 1906 by the use of a stannic stain, so it could be de distinguished from the M 1. The ogive was of the same shape as the M 1, and differed a bit from the shape of the 1906, but the difference was so slight as to be imperceptible.
Some of this ammunition reached the Service Boards. which by now had lost all of the old World War I machine gunners who so keenly felt the inadequacy of our ammunition in 1918. Our soldiers liked the lessened recoil of the new ammunition. More rounds could be carried for the same weight, etc., so the suggestion was made and carried through that it should be substituted for the M 1. In 1940 this ammunition with some slight further changes, was standardized as Cartridge, Ball, Caliber .30 M 2.

Remember that Gal. MacArthur rejected the choice of the .276 Pedersen for the Garand M1 because of the existing stock of .30-06 Mle1906 ammo, a stock that was already depleted by the time the Garand M1 was standardized in 1936...

M2 is not the same thing as M1906. The only thing they share in common is the projectile shape and lead core. Everything else is different.

The MacArthur story is a little oversimplified. He carried over the recommendation of the Ordnance Board, which was convinced by the existence of the ZH-29 and T1 Garand that a .30 caliber selfloading rifle light enough to meet their requirements could in fact be developed. The .276 cal's raison d'etre was entirely to allow a semiautomatic rifle to be made light enough for service use (9.5 lbs or less). With it being shown by 1930 that .30 cal selfloaders this light were possible, the need for the .276 evaporated, along with the challenges it presented. Keep in mind, at this time the US had entered the Great Depression, so there was no money for anything, let alone to retool every weapon for this new caliber.

But the fact remains that the sole motivation behind the development of the M2 was the need to reduce the "Surface Danger Zone" of the ammo, compared with the M1...

Yes, they just miss the opportunity to reduce ammo weight by 25% and at the same time increase the hit probability by 50% at 600 m... nothing really important after all !

Essentially yes.

Not compared to depression era concerns, certainly.

nincomp said:...

Years ago in one of the GPC threads here, I proposed the idea of using a neckless variation of the 7.62x51 to permit the use of a longer, higher-bc bullet.  My thinking was that this would permit a reduction of propellant and recoil while still giving acceptable long-range performance. ...

Personally I think that the TV ammo will be the real winner of this current NGSW porkfest - If their commercial ammo works as advertised.

Because you don't need to buy into a whole new weapon system when the benefits of tv neckless polymer ammo are just a re-barrel away...

Change barrels and maybe some springs, and your old weapons are now shooting "improved" cartridges. And the dimensions of the polymer case are done so that they work perfectly in existing mags and belts. And you still get some weight saving benefits.

Want to have a "6.5 creedmoor" ballistics in your 7.62 rifles and machineguns? "Here take these 6.5mm barrels and go have fun..."

Want to give an "improvement" on the 5.56 cartridge a try? "Here, take these barrels in 6mm and 6.35mm and give it a go..."

You could even play around with re-barreling .50cal rifles and M2's into 14.5mm platforms just for giggles.