In June 1943 the RAF's order of preference in weapons for use against tanks was given as: 1st 40 mm S gun; 2nd 20 mm cannon with Mk III AP ammunition; 3rd RP with 25 lb AP head; 4th RP with 60 lb HE head; 5th .50" Browning HMG; 6th 9 lb AT bomb. Only the first three of these were considered to be serious anti-tank weapons. Some comment on these preferences is necessary. The 20 mm AP Mk III, as mentioned in Chapter 1, was a tungsten-cored round of considerable performance which was, in the end, not adopted. The RP with 25 lb AP head could penetrate 70-80 mm, which compensated to some extent for its lack of accuracy. The RP with 60 lb HE head was discounted against tanks as it could only penetrate 25 mm, but this assessment rather underestimated the cataclysmic effect of detonating such a large charge against a tank.
The 9 lb AT bomb, jovially known as "Puffball", used a squash-head rather than a HEAT design and a fighter-bomber was expected to carry twenty-four of them, to be released in one diving pass at low altitude. Despite the success of similar (but smaller) Soviet and German weapons, Puffball proved unsatisfactory due to sympathetic detonations in mid-air (the explosion of the first hits setting off the others) and significant damage from blast and debris being suffered by the carrying aircraft. The 40 mm S gun, 20 mm AP Mk III and 25 lb AP were all considered capable of dealing with the German Mk IV tank and it seemed that the S gun-equipped Hurricane Mk IV would have a part to play in the forthcoming invasion of Europe. Despite this, all Hurricanes were withdrawn from European service in March 1944, just three months before D-day.