OK, I thought you were pulling our chain [joking], Grainger, but I've read your previous posts & realize that you are in France & seriously trying to understand how some things work. My apology for being less than serious.

Perhaps if you go here, you may find better explanations:

http://www.jblanchdatabase.co.uk/technical.htm

You may also wish to look into spending some time with a competent gunsmith or arms museum curator who can help to explain the mechanism to you w/a gun in hand.