Originally Posted by Drew Hause
Ted, Gene and FAB are the French experts. This is a long thread regarding French powders and proof
https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=618070

The double preliminary proof indicates the tubes were proved at 16,356 psi + 10 - 14% for modern transducer measurement
The single Crowned PT indicated final proof at 12,090 psi + 10 - 14% for a service pressure of about 9000 psi

[Linked Image from photos.smugmug.com]

I can't make a 'GAF' out of the Fs listed here
https://www.littlegun.be/arme%20belge/a%20a%20artisans%20identifies%20gb.htm#F

Drew,
Kind of you, but, for clarification, I am a student of the Darne gun. Anything else I know was incidental to seeking knowledge on that marque.

Best,
Ted