Well!!! Now that I think of it!!!!!! You are right!!!!!!!!O.K. got into a little discussion on the nomenclature of this round. My contention is that the sporting round is not really a .30-06, but should be the .30 Springfield Rimless, or some such designation. Splittin' hairs, I know, but interestin' none the less.
Consider: Springfield Armory (The U.S. Government one, not the Johnny-come-lately private firm of the same name.) began a search for a rifle to replace the Krag then in service from 1892. Using the Mauser rifle and 8mm cartridge, Springfield introduced a bolt action repeating rifle which was adopted by the U.S. Army in 1903. The .30 caliber M1903 round had a rimless bottleneck cartridge with a 220 gr. round nosed metal jacketed bullet. In 1906 the round was modified by shortening the case neck .07" and loading a 150 gr. flat based Spitzer bullet, full metal jacketed. This round is the Caliber .30 M1906 round from which the term ".30-06" was derived. But, the .30-06 lasted only twenty years, being replaced by the .30 M1 round in 1926. The .30 M1 was loaded with a 172 gr. boat tailed Spitzer full metal cased bullet. In 1937 the U.S. Army adopted the M1 Garand rifle as the standard infantry rifle. The M1 ammunition didn't function as well in the gas-operated M1 Rifle, and the M2 ammunition was issued to replace the M1 ammunition. The M2 was laoded with the 150 gr. bullet, at 2700 fps velocity.
However, when I was in the Army, in the 'fifties, I remember our ammunition overseas marked as "Cartridge, AP, Caliber .30 M2" and having a boat tailed bullet. These were from Lake City Arsenal mostly, bearing the "L C " headstamps.
But, my contention is the round is truly no longer a ."30-06" when any deviation from the 1906 specification is made.
Oh, I'll continue to use the term ".30-06" but this will still be in the back of my mind.
(Hard headed old nit-picker)