That's kind of what I assumed. There are indeed a lot of claims about the extra velocity of AI rounds, and these days they are undoubtedly true, thanks to cheap chronographs. But pressure and barrel length are another part of it.
A few years ago I hunted caribou in the NWT and one of the guys in camp had a .35 Whelen Improved, a custom rifle that he'd had built with a 27" barrel to "burn all that extra powder." He claimed to be getting over 2800 fps with 225 Ballistic Tips, and why not?
I have nothing against AI rounds, and indeed generally have a rifle chambered for one. I like not having to trim brass, but am not crazy about fire-forming, especially in a big game cartridge. Yeah, it's easy to do while working up loads at first, but if you shoot much brass does wear out and eventually you have to do it all over again. And there can be feeding problems, one reason my latest AI is a Ruger No. 1. Come to think of it, it's a .280 AI that uses already-formed factory brass!
On the other side, my friend Stevie Dogzapper loves AI's, but then he has been retired for a while and needs something to occupy his time.
