I’d be a bit more concerned with your magazine length. The 8mm Rem Mag converted to 358 STA has a COAL of 3.65”, the 300 Wby is shorter at 3.56”. For a long distance powerhouse, I’d be more interested in a 338 RUM, which already has a shorter cartridge length by 0.05” at 3.6”. .33 caliber bullet technology is far more abundant than .35 caliber and the .33 has more variable weights for use, which makes it far more adaptable to any game situation.
It will be next to impossible to find 8mm Rem Mag Brass, therefore you’ll need to find 416 Rem Mag Brass to neck down or screw around with deriving from a long 375 H&H variant.
The 338 Rum is easily formed by necking up available 300 RUM brass and trimmed to its shortened length at 2.76” in lieu of the 300 RUM at 2.845”.
Just a thought.
