I have meet many time mr Pedersoli and mr Chiappa of armisport, i made the same question and i havn't had a real answer on this, they say that this info is dangerous if it start to turn around the muzzleload people
Every single arms product here in Italy, or imported from other country, go to BNP, a governative structure, for a proof forced test, all the small marks on a weapon product in Italy are put by BNP after the test, a rumors say that they use a 30% of load more of a maximum load for smokeless arms, i don't know if they made the same for black!
BNP work also for normal citizen that have doubt about an old arm or about his personal reload cartridge, they certificate the safety!
Sorry for poor english
ciao
Rusty