Scottish Teeth:
There are a few burn rate charts on the internet such as:
https://hodgdonpowderco.com/wp-content/uploads/2023/04/updatedburnrateschart-1.pdf
Reloaders will often extrapolate, if that's the right word, and use data on powders with the closest burning rate to what they have.
With VihtaVuori, the higher the number, the slower the burning rate. Usually 6.5 calibres require slower powders than larger calibres and heavier bullets use slower powders than lighter bullets in general.
Regards,
Peter
It's interesting that you bring this up.
When 6.5x55 rifles started appearing in Canada, there were only a few sources for factory loaded ammunition or components.
CIL, Dominion Cartridge Co out of Canada and Western out of the US, loaded and distributed ammunition.
Rumor had it at the time that they didn't originally produce their own cartridge cases and bought them from European manufacturers, with their company logo stamped on the base.
They made their bullets and supplied their proprietary powders/primers. They made bullets in weights from 87 grains to 160 grains.
What was interesting was the powders they used. The factory powders were mostly in the IMR3031 burn rate and bulk, which is very similar to Norma N130, which most would consider to be on the fast side.
Century International and Ammo Mart, sold component packs, consisting of your choice of bullet weights, surplus powder, and surplus, Berdan primed cases, all made in Norway and Sweden. I still have many of the bullets and a few hundred cases, which all have "wooden" bullets and are filled with a very fast "flake" type powder, which works great for very light bullets or in 45 Colt cartridges.
Both of these outlets supplied enough powder, #44, which was made by Bofors, and has a burn rate almost identical to IMR3031. I helped Tom Higginson develop loads for the 6.5x55, which would be safe for use in the AG42b rifles and provide consistent reliability with feeding and extraction.
Tom already knew the burn rate of #44 powder was quite fast, but at the time the powder was developed by Bofors for the Swede, Norwegian, and Danish firearms chambered for the 6.5x55 the burn rate was "slower" than most other available types, and was bulky enough to be acceptable for most purposes encountered by the cartridge in the military firearms it was chambered in.
It wasn't until firearms with "stronger" actions, and components became available for sporting purposes, that people demanded more from the cartridge.
No surprise at all, as the same thing happened with several other military cartridges that were seconded for purposes other than which they were designed for.
Presently there are several very good powders, some of which are no longer being produced, such as RL26, which are suitable for some very spectacular loads in "modern strong actions"
Interesting as to how "perceptions" of what's acceptable have become, since the inception of this fine cartridge.