The adaptor was chiefly used on British armoured cars, e.g. the Daimler, which had been designed and built earlier in the war and could not be readily fitted with a larger gun. As an adaptor to the existing gun it could be removed so that normal rounds could be fired. This offered increased anti-armour effect but with obvious drawbacks in combat conditions. When crews discovered the special 'squeeze bore' ammunition was more effective than the standard 2pdr AT round even when not 'squeezed', the usual practice was to store the adaptors rather than have them fitted.