Best Powders for Heavy Rifle Calibers out of Short Barrel

[FrankenMauser]

I think you need to modify your general rule a bit. It's not just the bore size, its the bore size to case powder capacity ratio that determines whether slower or faster powders are useful.

Agreed. But I don't believe I need to modify the statement.
I believe my limitation of "...any given basic cartridge family" covers that.
I went with that limitation specifically to avoid getting into expansion ratios. Although it is the driving factor, I only felt like touching on the topic, rather than diving in.

 

[Archie]

Two different questions

If one seeks the highest possible muzzle velocity from any rifle, powder burn rate is determined by bullet weight (heavier bullet weight demands slower burning powder). The fastest muzzle velocity for a given bullet weight will be the fastest muzzle velocity in any length barrel. (Short barrels will be slower, but so will any other load.)

If one seeks the highest possible muzzle velocity in relation to the amount of powder used, use the fastest powder consistent with safe pressure.

So it depends on what is desired. For maximum performance, match the bullet weight to the burn rate. Heavier bullets require slower powder. One never achieves higher velocity with the theory of matching powder rate to barrel length.