Case capacity increases the attainable energy/velocity, no question. It's not linear - if you increase your case capacity by 10%, you don't get a 10% increase in muzzle energy even though you can put in 10% more powder and thus 10% more chemical energy. You might get a 5% increase in muzzle energy depending on a variety of factors. In other words cases get less efficient as they get bigger, even as they become more powerful.
Now we come to the .30-06. It's inefficient shoulder, low MAP, and the extra barrel length consumed by the longer chamber (barrels are measured from the breach face, which makes sense from a weight perspective) all work against it relative to the .308. What you will find when you do the math is that most of what the .30-06 gains due to extra case capacity is lost back due to poor design. All that remains is a trivial difference that only manifests in a very short list of powders, none of which have been named by the .30-06 advocates, possibly because their load data is as out of date as their cartridge.
As far as coyote, his behavior in this thread is so poor that at this point anything other than calling him ignorant is a waste of time. If he want to come back, admit he knows next to nothing about interior ballistics, and is willing to learn we can try again. But as it stands I will say nothing respectful to him as respect is earned and he hasn't. I have no problem engaging with others on the topic, but ignorant boy has proven that dealing with him is a waste of time.
Blah, blah, blah. Lots of words but no real, tested loads to back up your position. Why not? (Rhetorical question as the answer is obvious - you can't find any.)
i've been using a figure of 19% greater case capacity for the .30-06. If you accept 69 grains for the 30-06 and 56 grains for the .38 Win, the difference is really 23%. Use heavier bullets that seat deeper in the case, reducing interior space, and the % useful case capacity of the .30-06 increases when compared to the .308 Win.
Vis a vis the .308 Win, the .30-06 is limited in performance more by the SAAMI MAP than the cartridge design. The .308 Win starts out with a 2000PSI pressure advantage. Even so, the .30-06 can beat the .308 across the board using pressure tested data. I've shown tested loads from 110g to 220g that the .308 cant match and you've shown nothing but theoretical loads. People don't shoot theoretical loads.
The .308 Win is an excellent cartridge, which is why I've owned four and still own two. There are currently four .30-06 rifles in my safe. If I could only have one or the other, the .30-06 would win hands down.
Coyote Hunter - NRA Patriot Life, NRA Whittington Center Life, GOA, DAD - and I VOTE!
No, I'm not a Ruger bigot - just an unabashed fan of their revolvers, M77's and #1's.
