Thanks for that link, Anna: a fascinating refresher on the subject.
Here's a short clip of the Sam Willis event at Chalke Farm, although it doesn't include any analysis of the results:
http://www.youtube.com/watch?v=4-h4vQVmBdYI have a handful of Peninsular and Waterloo period musket balls at home - both British and French - and had always thought the most notable difference between the two was the size: the British ball being significantly bigger. Not very scientific, I agree, but easily distinguishable by eye.
Looking at a website comparing the French Charleville and British Brown Bess issue musket balls, that seems to be confirmed. According to folks who know their stuff, the Brown Bess fired a .75 calibre ball and the Charleville a .69.
I'm certainly no Napoleonic firearms expert, and my thoughts are only based on scrutinising a handful of musket balls, but I wonder why a closer examination (refused by the Queen in Anna's link) would have been needed - and what else it would have added to any verification of the type of weapon used?
On a side wind: If the report that the Queen refused permission for the Nelson ball to be examined is true, and if the request was made by a qualified and responsible organisation, I find that very disappointing. Surely - using state of the art technology - as Kester submits, it could have been done in a non-invasive way?