I have not bought the ammo but I have bought some of those bullets to play with.
They show a little over 1000 fps in the 44 special.
I may not go quite that far as I am using a 696.
They want a minimum of 750 fps but I doubt the hydraulic effects show up until after Mach 1 type speeds.
This claimed effect is very similar to the Woodleigh hydrostatically stabilized solid but with more of an "oil drill" type nose.
Hydrostatically Stabilised Bullets - Woodleigh Bullets
My main experiment with these is in the .445 Encore where I expect to get 2000 fps which is more like it for a bullet like this.
Since they are light for caliber it will be interesting to see just how much penetration they get in big game animals.
Not sure I would use these as a primary hunting bullet but would test them in a carcass the way many gun writers have.
In the 44 magnum I would expect them to zip thru any whitetail.
Almost all 44 bullets do.
Larger deer and elk with a shoulder shot who knows?