I know a little bit about these cartridges so might as well give my thoughts and opinions on the subject. Before getting into the AI cartridges VS. the Weatherby though, i'd like to express how much faith i have in the good ol 25-06 in it's own right. Few of us actually shoot at game over 500 yds away. I have but i don't like to and hope that i don't ever have to again. 400 yds is a very long shot on game. 500 yards is Waaaaay out there and, IMO, out of the realm of most guys personal abilities, most, and shouldn't be taken but by those who have earned the right, put in the time, effort, and knowledge, to do so.
So, how much do you gain with the Ai version over the plain 25-06? is it worth it? You have to first answer me this, is there a difference to you between the 257 Roberts and the 25-06? How about the 270 Winchester vs the 270WSM? The 30-06 vs the 300 Win mag? Each of these cartridge example groups have about 100-200 FPS difference between them shooting the same bullet. If you might favor one over the other because it can do "more", then you might be a fan of the AI line of cartridges because they basically do the same thing, more.
As far as the added difficulties in reloading for the Ackley IMP cartridges, i have found them to be easy as pie. When i need brass, i shoot factory parent cartridges thru my rifle and wa-la, i then have Ai cases ready to reload. I've not had to annul (sp?) to this point.
Factory 25-06 ammo runs out at about 3000 fps in the heavier bullets. Factory Weatherby cartridges run out around 3400 FPS. I seen loadings posted here and there of the 25-06Ai using the heavier bullets running about 3200 fps.
So, you have choices. You can shoot good high BC .257 bullets at 3000, 3200, or 3400 FPS thru the gun chambered of choice. If that matters to you for what you want to do, there you go, pick your poison, they will all kill, they are all very deadly on game. If i were to make up a 25-06 AI, i'd order up a barrel with a faster twist than what comes from the Factory. Seems to me, the twist on factory 25-06's limits velocity some, the faster twist would no doubt help in handling the heavier longer bullets one might choose to hunt game with. That's my $.02
Joey
"It's all about knowing what your firearms practical limitations are and combining that with your own personal limitations!"