Art,
Yep.
The main reason why the .30-03 case was shortened was advances by Du Pont in military rifle powders.
This was, by and large, still the infancy of smokeless rifle propellants.
Du Pont came up with I believe Military Rifle 15, which was higher energy and lower density than the powder originally loaded into the .30-03.
The original replacement bullet for the 220-gr. round nose was a 150-gr. flat base pointed bullet.
That was replaced by a 173-gr. bullet (and the powder changed to, I believe, MR 17 or 17 1/2). A couple of things became evident with that change -- recoil was higher, the heavier bullet had the same nominal muzzle velocity as the lighter bullet, and almost every military rifle range in the nation was rendered obsolete by the 173's MUCH extended range.
When development of the Garand started, and MacArthur ordered its caliber changed to .30-06, the 173-gr. loadings presented a challenge to John Garand that he never was fully able to solve.
The decision to switch back to a 150-gr. bullet finally made the M1 a truly workable proposition.
Remaining stocks of 173-gr. ammo were then earmarked for use in machine gun.