British arty Sexton II, 3 Kills, Tundra Winter. The Sexton II is a British tier 3 self-propelled gun. Modification of the Grizzly (M4A1 Sherman) tank, mounting the British 25-pounder field howitzer. Mass production was launched at the Montreal Locomotive Works in Canada, with 2,150 vehicles manufactured from 1943 through 1945. The Sexton II leads to the Birch Gun.