Just wonder that what if .276 Pederson was not rejected by Gen. McArthur and M1 Garand was made with detachable box mag would change USGI in WW2. US Army was fairly small before WW2 and the stock 30-06 would end out very soon anyway. It would be something like a Mini-14 with 20in barrel chambered in 6.8SPC today.

i suspect there would be a lot less .30 caliber cartridges out there.  and not very many people would be shooting .30-06.  there would likely be no ar10 or ar15 around and rifles would generally have wooden stocks and be more conventional looking in general.  and possibly the m14 would have succeeded in being select-fire.

The .276 was only slighty shorter than the 06, the Garand was designed for it and just happened to have a long enough receiver to be converted to 06. The Pederson rifle which was in competition with the Garand was not long enough and fell by the wayside.

The Garands enbloc would of held 10 rounds of the .276 Pederson (IIRC).  The .30-06 would still be popular, it would still have been used in the m1903s used by snipers, the BAR and in the Browning machine guns.  It would have have taken on a mystique of being very powerful and accurate.

On the other hand the .276 would become the "medicine" for any hunting in the US.  The adoption of the 7.62x51mm NATO would probably never happened.  Instead a .276 intermediate cartridge based on the .276 and the German 7.92x33mm Kurz would have appeared, something like a 6.8X36mm.

I have often wondered that myself.