The Collaborative International Dictionary of English v.0.48:

Case shot \Case" shot`\ (Mil.)
   A collection of small projectiles, inclosed in a case or
   canister.
   [1913 Webster]

   Note: In the United States a case shot is a thin spherical or
         oblong cast-iron shell containing musket balls and a
         bursting charge, with a time fuse; -- called in Europe
         shrapnel. In Europe the term case shot is applied to
         what in the United States is called canister.
         --Wilhelm.
         [1913 Webster]

WordNet (r) 3.0 (2006):

case shot
    n 1: a metallic cylinder packed with shot and used as ammunition
         in a firearm [syn: case shot, canister, canister
         shot]