Officially known as the 'Matilda Projector, Hedgehog, No. 1 Mark I, this fitted a Hedgehog 7-chambered spigot mortar in an armoured box on the rear hull of several Australian Matilda tanks. The projector was elevated by hydraulics adapted from the Logan traversing mechanism used in M3 Medium tank turrets and electrically fired either individually or in a salvo of six, from the 12 o'clock position;] the fifth tube could not be fired until the turret was traversed to 1 o'clock, to move the radio antenna out of the bomb's flightpath. Each bomb weighed 65 lb (29 kg) and contained 30 to 35 lb (14 to 16 kg) of high explosive. The range was up to 400 m (440 yd). Aiming was accomplished by pointing the entire tank; the mounting had no independent traverse, so accuracy was not spectacular, but adequate for the task. Trials at Southport, Queensland, in May 1945 were pronounced complete success, and the Projector would have been impressive against enemy bunkers, but the war ended before it was used operationally.