I'm not in favor of transferring an 'unknown' propellant, into a new cartridge case, and thinking everything is 'OK'. To me it is false economy.

I had a (6.5X53mm Rimmed) Dutch Mannlicher carbine and a box of 1930's vintage Dutch military ammo, at one time.

I did not want to shoot the old corrosive Berdan primed ammo. I made replacement Brass out of .303 British and .30-40 Krag cases.

I pulled the bullets from some of the Dutch cases, directly dumped the whole charge of square-flaked powder into a new case, and seated a pulled bullet.

At the Range, I fired the first 'reloaded' round, which produced a nice hole in the Bull's-eye.

When I slowly opened the bolt and withdrew the fired case, to inspect it, the 'spent' Boxer primer fell out of the expanded primer-pocket.

It had not been my intention to "Re-Proof" the Hemburg Arsenal metallurgy!

I was Lucky. I dismantled all the remaining "reloads" and burned the powder in my leaf-pile.

After this experience all future loads were "worked up" from Starting Loads of known propellants.