 However, British Army test results conducted with two Fireflys against a Panther turret-sized target demonstrated relatively poor accuracy at long range; a hit probability of 25.4% at with APCBC, and only 7.4% with APDS.In late 1943, the British offered the 17-pounder to the U.S. Army for use in their M4 tanks.General Devers insisted on comparison tests between the 17-pounder and the U.S. 90 mm gun.