07-10-2020, 09:29 PM
I would not hold my breath waiting for CFE BLK data for the ARC, I think it will be too fast and not nearly fill the case before max pressure is reached. Hodgdon in their info on CFE BLK says loads below 90% capacity will give wide extreme spreads and it does best near 100% case capacity or slightly compressed.
Generally speaking velocities follow a trend with the same cases necked up or down for different calibers, bullets of the same SD will often achieve similar velocities. It is easy to see this with the 308 and its offspring's. Some of that can be made up with powder selections but things like longer bearing surfaces of same weight bullets and expansion ratios come into play.
Generally speaking velocities follow a trend with the same cases necked up or down for different calibers, bullets of the same SD will often achieve similar velocities. It is easy to see this with the 308 and its offspring's. Some of that can be made up with powder selections but things like longer bearing surfaces of same weight bullets and expansion ratios come into play.