The 17pdr SP Achilles (officially 17 pounder, Self-Propelled, Achilles) was a British variant of the American M10 tank destroyer armed with the British Ordnance QF 17-pounder high-velocity 76.2 mm (3-inch) anti-tank gun in place of the M10's considerably less powerful 3-inch (76.2 mm) Gun M7. A total of 1,100 M10s were converted to Achilles, making it the second most numerous armoured fighting vehicle to carry the 17-pounder gun, behind the Sherman Firefly tank.
The name "Achilles" was officially a designation applied to both the 3-inch gun and 17-pounder versions (as Achilles I/II and Achilles Ic/IIc respectively) but was little used during the Second World War; at the time, the vehicle was called 17pdr M10, or 17pdr SP M10, or even occasionally, "Firefly". It has since become identified almost exclusively with the 17 pounder version.
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