Derar Jim, i guess
mitraille (metralha over here) belongs in a different typology, within a range that comprehends canister, grape shot, even shrapnel and the like. Being an ammunition that covers both sea and (mainly ?) land purposes, if differs from chain shot, which purpose fundamentaly contemplates navy warfare.
If i am wrong, please don't tie me to whipping post

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As a footnote, the term mitraille, in fact of French origin, has with them a few different meanings, although with a similar 'dimensional' attribution, like (money) small change and (chicken) giblets.