An article in Handloader some decades ago tested the .30-06 std vs. AI and iirc concluded that there was minimal difference in velocity if pressures were the same (using measurement of the pressure ring on the brass to .0001").
Looking at the Nosler manual it shows the 30-06 AI almost 3000 fps for the 180 out of 24" barrel. About 170 fps more than the regular 30-06. With the 200g there isn't much difference. If I didn't have a 300 H&H I might consider the AI.
Since the 30-06 Ai has never been SAAMI-ized, I wonder if they may have been loading the AI to a bit more than the 60K limit of the parent '06. That's really the only thing that would explain a 170 FPS gain using the same 180 grain bullet in both. More like 50 FPS max would be about the most that would be expected at the same pressure as the parent case.
Not that there is anything wrong at all with loading the AI (or, IMO, the parent case) to >60K PSI. I truly wish "they" would publish +P data for the 30-06 designed for modern rifles that are also suitable to the .270 Win at 65K PSI.
We (the handloading community) have managed to do this safely with the 45 Colt and 45-70, for example where data are clearly delineated by the firearms class for which they are appropriate.
Just my two cents,
Rex
