I would say you would be in the 3800-4000 range but your barrel is not going to last long. I would say after 300 rounds you may see an accuracy loss. Would probably need a 28-30" barrel to get the max velocity.
If I did not already have a 257 Weatherby the 257 STW might be interesting, I have not fooled around much with anything less than .25 caliber.
I think the 06 case is plenty big for that bore. The 240 Weatherby is equal to the 6mm/06. I have a wildcat off the 338 RUM case and it is necked to 7mm. I think that case is a better choice than the 7mm RUM.
I think the 06 case is plenty big for that bore. The 240 Weatherby is equal to the 6mm/06. I have a wildcat off the 338 RUM case and it is necked to 7mm. I think that case is a better choice than the 7mm RUM.
Not much. The 338 RUM case is .090" shorter. This allows a properly set up reamer, cut a chamber to have a loaded round be able to fit the magazine AND reach the rifling. This is not possible on a 7 or 300 RUM.
The 338 RUM has a slightly shorter length to the shoulder than the 300 RUM. It supposedly had to do with the bullet seating depth for the heavier 338 caliber bullets to be seated out long and still work in the standard length action.