The secret to the standard 458 is BM2 and 2206H.
You can easily get 2150 fps with a 500 grainer (which will handle anything on the planet).

The other thing to do on the Brno's with so much room in the mag is glue a bit of incertion rubber down the front of the mag box as this takes up some room and stops the RN soft points from deforming under recoil.