When looking at the loading manuals you must also consider what they do not say!
I like to look at the old cartridge loading data for rounds that began as BP and have been converted to smokeless and the preasures must be kept very low for use in the old guns.
Most of the time they do not get enough preasue to crush the copper pellet and achirve a preasure rating until they reach what they consider max loads for these cartridges with smokeless.
If I can duplicate that load using BP it will be a safe load either loaded in a cartridge or poured down the muzzle.
CPU units are valuable as comparison tools, and when the load was not heavy enough to give a preasure rating I consider it the sign of a light to mild load.
Most suggested max loads, in pyrodex or BP, for our BP guns will not even register on the preasure scale.
The only BP guns I have ever seen that were blown up were either short started, had a barrel obstruction, or were loaded with smokeless powder. Most of the barrel makers only fear blowouts at dovetail cuts that leave less than .020" between the bore and the outside world. They recommend a minimum of .050"
I have done blow up tests myself and after that I refused to believe the stories about the shreaded barrels brought into my shop by "friends of the brouther-in-law" who blew them up with "just a standard load of BP!"
