I think the ballistics I noted would be easy to get. Consider factory Norma or maybe it was RWS 8mm Mauser ammo with 224gr. bullets at 2,400fps+ and 196gr. TIG's at 2,550FPS+. Due to the larger bore size and greater expansion ratios, the 9mm, 9.3m and 9.5mm will deliver progressively higher velocities with the same bullet weights at the same pressure. ie: the 9.5 will deliver higher velocities with any bullet weight than will the 9.3mm, etc, etc.
; Given the action is in good shape with the appropriate heat treatment (of which I have no doubt) the action will easily handle 'normal' pressure for the .473" case. I believe there is no reason whatsoever to limit pressure to the current pre-1900 US specs for 8mm ammo. A reasonable pressure would be 57,000PSI(of Norma and RWS) to 61,000PSI which is still short for that brass in current modern loadings. At those 'normal' sub-max levels (63,000psi to 65,000 is normal max for that case size), the 9.5x57 should easily do 2,100fps with 300gr. bullets. Since the 9.3x57 will do 2,100fps or more with 286gr., the 9.5 should do the same with the next heavier bullet weight at almost identical pressures.
; I would use modern RP, WW or Fed 7mm Mauser brass for this rifle as it has shown itself capable of showing normal expansion at pressures well above 60,000 psi. An alternative is to use .270 .30/06 or .280 brass, expanding the necks in a .357 die first, then FL sizing in the appropriate FL die with the expander system removed will form the brass in one step. Final neck expansion can be done once the brass is trimmed to proper length and chamfered by another trip through the same die, assembled.
; Of course, there is nothing wrong with driving a 286gr. of any diameter at 2,150fps and using that for all big game shooting. It will work just fine. I just like 300gr. .375's I guess. BT- the 235gr. Speer would be a tremendous bullet in this 9.5mm ctg. Recovered 235 Speers from 4 moose showed excellent expansion, penetration and killing power when driven at a pokey 2,600fps from a .375H&H. I suspect the 9.5x57 might attain 2,450fps with this bullet - excellent for all-round use.