Many thanks for you elaboration on points made by Kevin.
Their is a lot we still dont know about napoleonic artillery. No period manual says what happened to the wooden sabot, the iron plate in the bottom of the cannister (assuming french cannister) and the cannister itself upon firing of the round. We know the effect of the ammunition, but not neccisarily how it was achieved.
As I tried to point out, the gunners of the period were using educated guesses, as with the horse analogy.