British tank crews were trained to fire on the move and the armament was mounted for optimum balance such that the gunner could aim with his body rather than use geared elevation. This reduced available space inside the turret. Both early Cruiser and Infantry tanks carried the Ordnance QF 2-pounder, a 40 mm anti-tank gun, a good match for the contemporary German 3.7 cm KwK 36, and effective against tanks of the time but increasingly outclassed as the war progressed. Production shortages caused by losses in France and the Battle of the Atlantic forced the British to delay widespread introduction of the Ordnance QF 6-pounder (57 mm) anti-tank gun until 1942.