Some mounted machine guns and artillery pieces are equipped with metal armor plates to protect the gunners from sniper fire and shrapnel from explosions. Salvaged metal plates can sometimes service as improvised gun shields; in the Vietnam War crews of armored fighting vehicles and patrol boats would attach metal plates to the machine guns.
Gun shields fell out of widespread use after the Vietnam war, but they have seen a resurgence in popularity during the 1990s. Israeli military analysts began urging the use of gun shields, pointing to the grave risk to soldiers exposed to fire from automatic weapons. In particular, it was noted that many casualties were hit in areas not protected by body armor or a helmet, such as the neck or face.
The U.S. began using gun shields during the 2000s-era wars in Iraq and Afghanistan. The major drawback of gun shields is that they limit the visibility of the user to the front, though new designs such as the Transparent Armor Gun Shield (TAGS for short) will alleviate this without sacrificing user protection.