Depends on what you consider relevant; I edited my post while you were posting this with a doctoral thesis about the history of British rifle developments that is mostly about the EM-2 and by association the .270/.280 development:
https://kclpure.kcl.ac.uk/portal/en...86(5d9a29fb-ced6-4d8e-bf3f-987f3db7b5b9).html
Ah, Matt Ford. A friend of mine!
The .280 predates the US-UK testing, but it was developed partially in anticipation of that test as well as to appease a faction within British arms development. By the time the test rolled around the round they developed had abandoned the 2000 yard delusion.
Really? Then why did they go to the trouble of developing the TADEN MMG?
http://www.dtic.mil/dtic/tr/fulltext/u2/896859.pdf
If you look at the 1950 testing document (p.20) the the average velocities at 78 feet from the muzzle for the .280 round average around that of the 7.92 Kurz. The muzzle velocity was probably close to that of the 7.62x39 of the AK-47. So whatever was laid out in 1947 or before was discarded by 1950, as the round actually tested was optimized for 500 yards or less. By the 600 yard mark it was dropping off substantially, though (without checking ballistics) probably less so than the 7.92 Kurz was at 400m.
So I guess .303 Mk. VII wasn't a 2,000 yd cartridge either, eh? Because the .280 was explicitly designed to have the same midrange trajectory height - which is probably why the original load specification has a nearly identical muzzle velocity and BC...
And as cited it never was used in war, ultimately being replaced 10 years later with the M2 ball that went right back to the 1906 design with a different metal alloy and improved propellants. Why compare with the M1 that was abandoned long before WW2 broke out?
https://en.wikipedia.org/wiki/.30-06_Springfield#History
So in 1932, they made the decision to abandon the .276 Pedersen despite the fact that the .276 outperformed a round whose development wouldn't begin for another four years?
You also seem to be neglecting the fact that M2 Ball was not the primary battle round of WWII. M2 AP was. It had a much heavier bullet and better distance performance.
Fair enough. Still, doesn't mean for what it was with hindsight that the Pedersen round wasn't ultimately better than the M2 Ball that the US went to war with.
You know what would have been worse? Not adopting a semiauto at all because you can't afford to change over to the new "better" round during the Great Depression.
I am not sure that the Hindsight Warriors really understand how narrow a thing the M1 Garand's adoption really was. Might try cracking Canfield's huge tome on the subject.
Check out that thesis I posted, it gets into the full picture of the development of the .280. Yes the .270 was stillborn, but not necessarily over the MMG requirement.
I've got no idea what Dr. Matt thinks, it's not like I'm personal friends with the guy and we share notes all the time or anything.
The round used in the tests was a T104, which was slightly lighter and had 35% more propellant behind it (not sure about any differences in powders used between the British and US). It could stay supersonic longer due to substantially higher muzzle energy, which helps it avoid for longer the transsonic issues flat based rounds run into as they slow down.
T104 had a shorter supersonic range (by about 30 meters) than .280/S-12 with the original muzzle velocity of 2,415 ft/s. So there goes your theory.
The fact is that the .280/30 was clearly designed to retain energy well out to 2,000 meters, and - however select individuals felt at any given point in time - the .280 was always designed to give the option of being a good MMG round.
Again, depending on what role you want it to fill. The round tested in 1950 was designed with an anticipated 500 yard normal max combat range with a 600 yard max effective range, courtesy of that thesis I linked earlier in this reply and excerpts I edited into my previous post.
Also on p.19 they cite using 130 and 140 grain lead cores for the .280 and 150 grain lead cores for the .30 as a control group; groups are significantly tighter, but not excessively so.
So the data on p.18 is using lead cores with a heavier US round and the lead cored .280 ones.
Which shows that the issue isn't simply the steel cores, its the ranges that the rounds are designed to be fired at. Using the info from the thesis I cited (check out my previous post that was edited) the Brits by 1950 produced a rifle round meant to be used at 500 yards or less and controllable on full auto at short ranges. This was NOT a 2000 yard round.
Again, you need to read up more on the subject. You're inferring things that are easily refuted by additional context. And further, I feel as though I've done enough of your own legwork for you.