The question is dangerous in that broad generalizations are required to answer it. ...
AMtrico,
Jerry and every one else responding are correct. The problem lies in the fact that proof law was not static. The "standards" were not created across national boundaries for some time.
The British had proof standards in 1813. While the French had their own standards. We can be pretty sure that they were not in harmony at this point in history.
In 1910 the Austro-Hungarian Empire decided that the Belgian proofs they had been accepting since 1893 were no longer safe. The Belgians were besides themselves over this. After much negotiation, the proof house of Liege changed their methods, loads and powder.
In Germany in 1939 a new set of Black Powder standards was introduced.
This list could go on decade by decade, country by country.
You asked about "fluid steel" barrels. Well then the date and country of manufacture become even more important. For a long time, only the most expensive steel could handle greater pressures than damascus barrels. For a recent discussion here about steel barrels.
http://www.doublegunshop.com/forums/ubbt...;gonew=1#UNREADA better approach woud be for you could to post photos of your gun. Be sure to take pictures of all the proof marks. State as much as you know about the maker and the gun's current condition. It is just easier. I understand you are trying to be safe, as we all are.
Pete
