Yes, we tried them with Richard Graves 277 Allen Mag(338 Lapua) and they did not work well with this brass. They did round the shoulder out slightly but not enough to do any good.
ALso, you beat the HELL Out of your press trying to form the cases.
If they designed a cradel support that you could sit on an anvil or something like that they would work much better but beating on your press like that is like beating your wife or child, not for me!!!
Corn meal is cheap and easy to use so that is what I recommend, you get 90-95% formed cases as well that are suitable for full tilt accurate loading as well. With the hydro form dies you will still need to fireform to sharpen the shoulders.
It is a good idea and in the smaller rounds with thinner case walls it may work very well but not with the big stuff. I do not recommend them for any of my Allen Magnums.
Kirby Allen(50)