Here's a link to a previous discussion on handgonnes. Some of the links may be out of date, but it's a start... http://www.wolfeargent.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=1&t=000323 I had a book on handgonnes that now I cannot find. Had a few pages of Albion in the UK demonstrating the sequence. I might have lent it to Chef and forgot about it.
http://www.albionsmallarms.co.uk/1502inuse.htm
Part of your answer will depend on the grain of the powder (how finely ground it is and quality). After thoroughly inspecting (and have inspected) the handgonne, I would work up using a small amount of powder firing a paper blank. Clean it thoroughly each time without exception. This way you get into the habit of proper handling and the delayed flash that comes when firing the handgonne.
While not historically period, you might want to use safety goggles/glasses and even a dust face mask.
[ 03-04-2009: Message edited by: Friedrich ]