"...how you arrived at this?..." 30 odd years of shooting one. In all that time I have never seen case lots of milsurp .30-06. Including while working in a gun shop that sold cases of milsurp ammo.
There was nothing but commercial ammo and nothing in writing about not using any .30-06 ammo in an M1. Never saw nor heard anything about it until seeing it on the Internet. The box or two of 220 grain Silvertips did nothing to my rifle. 165 grain hunting bullets and 168 or 175 grain match bullets shoot better though. All of 'em with IMR4064, IMR4895 or Varget. IMR4064 gives more consistent accuracy than IMR4895. Never used Varget myself, but it is proven to give excellent accuracy too.
"...Garand was designed to function at approx 2700 fps..." The rifle was designed to use .30 M1 ammo with its 174.5 grain BT bullet at 2640fps using IMR4895. When the W.W. I vintage supplies of ammo was used up, in about 1936, the M1 ammo was issued and found to have too much range for U.S. National Guard ranges. The bullet weight was dropped to 152 grains at 2700fps(also with IMR4895) and the new .30 M2 ammo was standardized in 1939. In 1940, the MV of the ball round was raised to 2800fps to match the ballistics of the .30 AP's 168 grain bullet. This was the ammo used in W.W. II.