Barnes sells a 80gr TTSX. I'm getting over 3350 FPS in a 22" .257 Rbts.
I'm with John on this idea, I had considered it but even at 4000 feet elevation I won't be launching them from the right rate of twist.
The Marlinowners thread I mentioned had some of the members showing how they might shorten a Barnes to work in the standard 25-20 barrels, it involved making a flat hollow point out of them by substantially trimming back the nose, and it might even involve trimming off some of the base to get them short enough. Then comes the experimenting to see what terminal ballistics might look like.
Thanks for the idea though,
Geno