If you pay attention to the photographs of equipment from the Second World War, and then look at the pictures of exactly the same (by type) modern technology, you will notice one extremely curious feature. In the middle of the last century, heavy machine guns in most cases do not have any protective equipment to cover the shooter from enemy bullets. Why? Indeed, from an engineering point of view, installing an armored shield is generally a mere trifle.
As all ingenious things sometimes turn out to be extremely simple, so the answers to the seemingly most confusing questions lie literally on the surface. Moreover, it should be understood that what seems simple, understandable and obvious today was not necessarily so in the past. This is exactly the situation with armored shields on machine guns during the Second World War.
The idea of the need to install a shield on a machine gun machine gun actually appeared before the First World War. Suffice it to recall what the famous Maxim machine gun looks like, which was just equipped with just such a protective accessory. However, most other heavy machine guns did not have anything like this, and all because when it comes to mass production of weapons, the eternal struggle of military and economic rationality immediately begins.
Most of the heavy machine guns at that time involved installation at a prepared firing point in the trenches behind the parapet of the earth, which undertook any kind of protection for the shooter. Therefore, there was simply no urgent need for shields. Anti-aircraft machine guns, which were installed on the turrets of tanks during the Second World War, had just begun to appear, and therefore neither side did not make shields specifically for them.
There were, of course, exceptions. However, they tended to stem from the original design of the technique. The simplest example: German armored vehicles, which had front armor shields for MG machine guns mounted above the driver's cab. At the same time, if a machine gun was also placed on the back of the armored car, then the latter did not receive any shield.
Even after the end of World War II, tanks and armored personnel carriers equipped with anti-aircraft machine guns were far from always equipped with protective equipment, despite the fact that in the 1950s, hand-held small arms were once again actively developing. The era of providing maximum cover for a soldier began only 30-40 years ago, and not at all because of some surge of special concern for soldiers, but primarily due to the fact that weapons manufacturers had economic opportunities to spend money, including on such, it would seem a trifle.
Continuing the topic, read about how do fighters know how many cartridges are left in the storeif only two are visible from above.