I could write a book on .30, .338. .35Whelen but it would only rehash most of what has already been stated.
I rebarreled my Interarms MkX to .338/06 in 2003.
I had 30/06 barrel replaced in ‘21...
I had originally planned to do a .35Whelen but got a Adams &Bennet barrel for $59 from Midway...
I scrounged and located many boxes of dusty set asides and partial boxes. Bought out the last of 5-boxes of 180gr Ballistic Tips at Ga Arms...
I agree with Jon Barsness; their is precious little difference between the three, with advantage going to the .30 due to ballistic coefficient and sectional density.
However, I do agree with Jack O’Connor that in comparing the .30/06 with the .270, the ‘06 will tend to make’EM FLINCH a little harder when hit...Meaning the .35Wh3len...
I dearly love my .35Remington Marlin M336C for deer and pig hunting. I load up a 200gr RN to 2,250fps. It’s a “stomper” Likewise my .358Win BLR-81 would be “more better” except it’s got a terrible trigger, and is just too pretty to haul around in an aluminum boat with muddy boots and wet gun cases...
Besides, it all moot now... In 2010 I ran up on a Ruger M77MkII African .375Ruger at a LGS. It was getting no love as it had a “knocked off” rear sight. I bought it for pennies on the dollar. Sent it back to Ruger who replaced the barrel for a VERY REASONABLE price.
So, the Ruger is in place in case we have a Velociraptor season, or an elephant escapes from the Atlanta Zoo. I’ve found all sorts of .375 bullets in dusty boxes or plastic bags at flea markets. 250, Sierra 250’s in a plastic bag for $27.00! A box of 50, 300gr Nosler partitions for $19.95... 200 Nosler 260gr Accubonds for $40.00. And 500 Hornady 270gr RN (pre interlock) fo $17.95/100.
I’m set for bullets! Not to mention some Speer 235’s and Hornady 225gr Spitzers (discontinued)...
I also have a Colt Lt. Rifle in ‘06 that gets the pick if elevation is above 8,000’.
Too many choices!!!