I have not looked at my loading charts yet, but my gut tells me to say that .358 Win. pressures may be a bit high for your M-96. I believe the 9.3x57 has velocities at just over 2000 fps with 286 gr. bullet; while the .358 Win. goes about 2300 with 250 gr. Along with a substantial increase in pressure. I'd back off 10% at least to start, and see if the rifle shoots to the original sights.

Good luck.

Mal