in the turret, the hull-mounted machine gun being removed to increase ammunition storage for the main gun. A .50-inch (12.7 mm) M2 Browning heavy machine gun was also fitted on the turret roof, though many crews removed it, due to its awkward mounting and position near the commander, which limited a full 360-degree view when the hatch was open. In 1945, some British Fireflies were fitted with a rail on either side of the turret for two "60 lb" high-explosive 3-inch rockets. Called "Sherman Tulips", these were used at the Rhine Crossing by the 1st Coldstream Guards. The rockets, accurate when fired from aircraft, were less accurate when fired from a stationary platform, such as a tank, as they had little initial slipstream over the fins. The RP-3 was only effective when its 60-pound warhead hit the target. Production and distribution Three different variants of Sherman Firefly served during the Second World War, each based on a different variant of the M4 Sherman. The Firefly conversion was carried out on Sherman I (M4), Sherman I Hybrid (M4 Composite) and Sherman V (M4A4) tanks. Some sources state that several Sherman IIs (M4A1) were converted and used in action, but photos allegedly showing these conversions are in fact views of the front half of Sherman I Hybrid Fireflies. To complicate matters, a very small number of Canadian licence-built Sherman IIs (M4A1), the Grizzly, were converted to Fireflies in Canada and used for training, but none saw action. The majority of Shermans converted were the Sherman V/M4A4 model, of which the British received about 7,200. The Sherman VC and IC variants are easily distinguished by their lower hulls; the VC having a lengthened hull, and a larger gaps between the suspension units. They employed the three-piece bolted transmission housing. The Sherman IC usually sported the cast transmission housing. The Hybrid can be distinguished by its upper hull, which is cast and gives it a distinctive curved look in comparison to the more boxy hull of a typical Sherman. Production of the Firefly started in January 1944 and, by 31 May, some 342 Sherman Fireflies had been delivered to the 21st Army Group for the D-Day landings. As a result, British tank troops were composed of three standard Shermans and one Firefly. The same distribution occurred in Cromwell units, but this caused logistical problems, as each Cromwell troop then needed to be supplied with