I would be interested in what sort of performance you are getting with your 25-06AI that are within 50-75 fps of the 257Wby. I have owned a couple of each and in my experience the 257Wby is a very substantial gain over any 25-06AI.
I'll even go first. 257 Wby with 26" barrel. 100 grain bullets go 3700+ fps. 110 Accubonds go 3550 with a very mild load and 75 grain V-Max's run 3950 fps. The V-Max's are literal tack drivers and the 110 Accubond's in the 3/8th MOA range.
My 24" 25-06AI's ran 200+ fps slower with the same bullets and blowing primers. If you cripple the 257Wby with a 24" barrel they run 100 fps slower.
I owned both of mine and compared them side-by-side. Both were 26" 1:10 twist barrels using the same bullets.
I average (deepending on weather conditions) around 3,350-3,375 FPS with 115 Bergers in my .25-06 AI using IMR 7828 SSC, Winchester .270 Win brass, and Federal 210M primers.
I would like to know how you are getting 3,700 FPS from a 100gr bullet in a 26" .257 Wby... I don't even think the Norma/Wby brand brass could hold together at those chamber pressures. Factory Weatherby brand ammo is already hot and 110 Accubonds are only around 3,450 FPS...I'll be glad to go take a picture of one of the boxes in the safe, if you'd prefer... That means you're pushing a 10gr lighter bullet over 250 FPS faster. Seems outrageous. I'm also calling ******** that your 110 Accubonds were going 3,550 on a "mild load" in a 26" barrel...That's just not possible. With 115 Bergers I was getting around the same 3,450-3,460 FPS and that was pushing it on the upper end with slower burning powders and still getting ejector swipes and flattened primers. Now, the 75gr V-Max... I can believe those were going almost 4,000 FPS. But with the other 2 loads, I think you need to get a new chronograph.
Also, I would like to know how you can compare a 26" .257 Wby to a 24" .25-06 AI and claim that's even a fair comparison?
Also, you just said if you "cripple" the .257 Wby and cut it down to a 24" barrel, you move the increment to around 100 FPS difference... The same thing happens when you add 2" of barrel to the .25-06 AI... The 25-50 FPS discrepancy between your rifle and mine, can be explained in something as simple as powder lots, barrels (some are faster than others, some slower), or even the type of powder we use, or even the difference in the reamers used being slightly worn or slightly out of spec, or slightly different in specs...
There's too many factors to even argue about trying to claim that I'm wrong, and how your precious favorite cartridge is bigger and better than mine. I really have better things to do than argue how a 25 FPS difference in 2 completely different rifles is even worth arguing about. Of course unless you're still wanting to act ****y and hold a grudge about what happened with my Weatherby, because that's your favorite brand of rifles, and you're still holding some sort of weird personal butthurt grudge over that situation that didn't affect you at all in ANY way shape or form... Then that explains why you would pick something as small as a 25-50 FPS difference to be petty about. It's the internet, don't take everything so personal.