Maybe this will be helpful.
I spent a couple summers playing around with 180 gr Nosler Partitions in preparation for some Newfoundland Moose hunts. I loaded for a 7m/m Rem and a couple different 30-06's. After much shooting I really couldn't see that much practical difference between the 7 m/m and the '06....and yes, I know there is a difference... but given my shooting ability and the ranges at which I would be shooting, the 30-06 seemed to be the logical choice. So then it occurred to me that if I were to forsake the magnum case and go with the 06, that what I wanted was a "maximum" 30-06.The whole concept was how to get the most out of an '06 and 180 gr. bullets safely.
What followed that summer was me in hot pursuit of the obvious. I burned through a number of different powders, H4831, a couple of the 4350's, RL 22, RL 19,RL17 and at the end, Western Powders Hunter. When all was said and done, I arrived at 57.5 gr. H4350 for the best accuracy and velocity....just a snit under 2800 fps. Hodgdon lists that load at 49,300 CUP, NOT PSI, by the way. I. I relearned a lot of the things that were always obvious, like for example....that 24" barrels shoot faster than 22" barrels. ...duh. So, my "maximum" 30-06 needed a 24 inch barrel. $450 later, I had a 24 inch barrel on my Rem 700 and a load that tickled 2800 fps with good accuracy....right? Well, not quite, there was a certain Montana gunwriter who had mentioned that he was shooting Hunter powder and was getting good accuracy and a bit higher velocity with about 57-59 grs. of Hunter. I tried it and it shot poorly. I posted my result here and that certain Montana gunwriter responded that he had used a magnum primer not the WLR primer I had used. Back to the reloading bench and the range and....the velocity was higher by about 50 fps than the the H4350 load and the accuracy was even better. The hunter load, 58.5 grs. as I recall, shot even better and was choreographing about 2850 with excellent accuracy. This, finally, was my "maximum" 30-06 load. Perfect. Unfortunately, this was two days before I was to leave for Newfoundland. Too late to make any changes. Since then, I have knocked off two moose with one shot a piece with the H4350 load. The load using Hunter would have been more...well, more "maximum"...and in the end, it didn't make any difference.
In the end, trying to push the 30-06 beyond 60,000 psi really won't get you very much... you can do it, but you are clearly at the point of diminishing returns. If you choose to push it further, then a case load of Western Hunter, somewhere north of 59 grs. would be the place to start....but I don't recommend it.
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