the British Army had abandoned them by 1942 and the Wehrmacht by 1943, while the US Army never adopted the weapon, although the USMC used Boys anti-tank rifles in the Pacific Theater. However, the anti-tank rifle remained in Soviet use during the conflict due to the importance it occupied in its doctrine of anti-tank in-depth defense, first demonstrated during the defense of Moscow and again during the Kursk battles. This became particularly true later in the war when the Red Army assumed an almost constant offensive, and anti-tank in-depth defensive deployments were used for protecting flanks of the operational breakthroughs against German tactical counterattacks. By firing on the lighter armored infantry and support vehicles (e.g. artillery tractors) the anti-tank rifle units helped to separate the supporting infantry ("panzergrenadiers") and artillery of the German tanks and so forced the tanks to halt at short distances from the concealed anti-tank guns leaving them exposed to fire from larger, longer ranged anti-tank guns. PTRS-41 semi-automatic anti-tank rifles were also used for sniping since an additional tracer round enabled rapid fire adjustment by the gunner. Although optical sniper scopes were tried with the PTRS-41, the weapons proved too inaccurate at sniping distances (800 m or more), and the recoil too much for effective use of the scopes.