Pretty sure we've discussed this issue a number of times here. And I know Doc Drew has posted information from contemporary literature, back when a lot of people were still shooting Damascus. The conclusion, as I recall, is that you don't need to go ultra low with pressure in Damascus barrels--assuming the gun is in condition to shoot in the first place. Many people looked for 5-6,000 psi recipes. Others suggested that if a gun won't handle something in the range of 7500 psi, you probably shouldn't be shooting it.
And of course there are Damascus guns which have been reproofed to current (or previous) nitro pressure standards. In which case you've got pretty solid guidance. If it's Brit and has a current reproof--either STD or the previous 850 bar--the service pressure standard is 10,730 psi.
