The Comet was the best British tank of WW2. Its 77mm gun fired the same ammunition as the 17 pounder gun from a shell case based on the British WW1 anti aircraft gun. The reduction in villosity did not have a too negative affect on the APDS shot and the Comet could still take on a Tiger or Panther at range.
The Ontos ("Thing" in Greek), officially the Rifle, Multiple 106 mm, Self-propelled, was an American light armored tracked anti-tank vehicle developed in the Used exclusively by the Marines.... Via ~ The NAM