The first assault rifles were used by Russia in World War I in small numbers , but the Germans were the first to use assault rifles in large numbers . Rifles that meet most of these criteria , but not all , are technically not assault rifles despite frequently being considered as such . For example , semi-automatic-only rifles like the AR-15 ( which the M16 rifle is based on ) that share designs with assault rifles are not assault rifles , as they are not capable of switching to automatic fire and thus are not selective fire capable .