I know Donnley lists the capacity of the 9.3x62 as being 74.8gr.,however the two I personally measured that were fired in a factory 9.3x62 Styer, have 78.2gr. water capacity. This is identical to my current .375/06IMP if I use .35 RP Whelen brass and 80.0gr. capacity if I use WW '06 brass for either.
: Most .35 Whelen data is loaded to 1920 .30/06 spec. pressures fo around 49,000CUP near as I can figure, while the .338/06IMP is loaded to the much higher .270 Win levels. The difference in pressure is around 6,000 to 7,000PSI. This is why the .338/06 is shown to best the .35 Whelen with 250gr. bullets, which is impossible if both are loaded to the same pressure.
::: hoppdoc - The 9.2x62 would be a very good choice for your Mannlicher, however, so is the .35 Whelen. If loaded to normal for the US-type pressures, the 9.3 x 62 will beat 2,500fps with 286gr. quite easily, and will also do 2,650fps. with 270gr.Speers One only needs BLC2 for this venture, or H4895 Extreme for very slightly reduced speeds. This is why Scovill used the 9.3x62 case for the original .375 Hawk/Scovill. The shorter neck improved the capacity slightly and of course made it his case, rather that him merely building a .375 /06IMP with stndard .454" neck. The reason my .375/06IMP has greater capacity than a .375/06IMP, is it's .460" shoudler, .470" base and same neck as a 9.3x62. I believe the chamber was cut with the oversized Gibb's body reamer, then standard neck throater.