> chain shot

I think these two were distinct and different armaments, curly. My understanding is that langrage was an informal mess of old scrap iron packaged into cannister form, spraying out in a lethal cone blast to 'clear the decks' and damage tophamper too, whereas chain-shot and bar were specifically designed for longer reach and to take down rigging and spars. As you say, an ugly job is war.

http://www.aeragon.com/o/am/a-03.html

As to the etymology, it sounds like it ought to be from French ~ l'angrage or l'engrage - but there's no obvious trace I can find.