High Quality Content by WIKIPEDIA articles! The 17 pounder, Self Propelled, Achilles was a British variant of the American M10 Tank destroyer armed with the powerful British Ordnance QF 17 pounder anti-tank gun in place of the standard 3" (76.2 mm) Gun M7. With a total of 1,100 M10s converted, the 17 pdr SP Achilles was the second most numerous armoured fighting vehicle to see service armed with the 17 pounder gun, behind the Sherman Firefly.