Hand grenades of the Mk III / MK3 family (USA)
As is known, the first land units of the United States Army hit the fronts of the First World War only in the middle of the autumn 1917 of the year. They immediately had to experience all the main features of the current battles, including a long stay in their positions and battles for trenches. American soldiers had a variety of weapons at their disposal, but it soon became clear that not all of the available samples met current requirements. Moreover, some of them may even be a danger to their soldiers.
In the First World War, the United States entered, having armed with several types of hand grenades. The army had products both domestic and foreign development. They were egg-shaped grenades with a metal body, which exploded and scattered around a large number of high-speed fragments. In general, such weapons suit the military, but it soon became clear its negative features.
Grenades Mk III of the First World War. Pay attention to the curved top cover. Photo Usmilitariaforum.com
In practice, it was found that the power of the available grenades is excessive, and in certain circumstances they can be dangerous. Thus, during a battle in close trenches or dugouts, a grenade could strike with its fragments not only enemies, but also its own fighters, while the risks remained at sufficiently large distances. For example, the fragments of the Mk II defensive grenade maintained a killer effect at distances up to 15-20 m. Thus, the army needed a new grenade capable of hitting the enemy without risking their soldiers.
Already in March, 1918, the American industry presented the latest grenade that meets the new requirements of the army. It was distinguished by simplicity of design and production, and therefore could soon enter the series with the subsequent delivery to the troops. For additional simplification and cost reduction, the authors of the project used some ready-made components.
Within the framework of the existing nomenclature of infantry weapons, a new grenade was designated Mk III. This name was maintained until April 1945, when the Roman numeral was replaced by the Arabic one. From that time until now, the grenade was called MK3 (the spelling of the Mk 3 is also encountered).
The main objective of the new project was the removal of the shell, crushing into fragments. To reduce the risk of a grenade was supposed to hit targets only with the help of a shock wave. This problem was solved in the simplest way. Designers abandoned the metal case in favor of a cardboard product with metal inserts. It was assumed that during the detonation of the charge the cardboard will collapse without forming dangerous objects. At the same time, the appearance of secondary fragments — fragments of various destroyed objects of the environment — was not excluded. However, they were much less dangerous than fragments of a metal case.
The first version of the Mk III grenade received a cylindrical body made of cardboard of small thickness. From above, it was covered with a curved metal lid with a thread for the installation of a fuse. Below on the cardboard tube was a metal disc bottom. The entire internal volume of the body should have been occupied by an explosive in which a cylindrical channel for the igniter was provided.
Based on considerations of unification and economy, they decided to equip the weapon with a fuse from the British grenade William Mills. This product had a body in the form of two connected tubes and a head with a shock-safety mechanism. It consisted of a spring-loaded drummer, which interacted with the primer-igniter and igniter cord. In the cocked position, the firing pin was blocked by a side pressure lever held by a check with a ring. Inside the grenade, the fuse was held with a thread.
In the existing case it was possible to place half a pound (227 g) of explosive. The charge was made of TNT, but there is information about the use of other types of explosives. Apparently, similar features of serial grenades depended on supplies and could be different in different batches.
The cardboard case of the Mk III grenade was painted black. A yellow marking was applied over it indicating the type of product, date of manufacture, manufacturer, type of explosive, etc. Finished products are offered to be packed in wooden boxes. At the same time, the fuses were transported separately, in a special compartment of the closure.
In a combat position, after the installation of the igniter, the Mk III grenade had a total height of no more than 140 mm with a case diameter of less than 55 mm. The side lever slightly increased the diameter of the product. The total mass of a grenade with a 227-g charge is of the order of 400 g.
Fuse from the grenade Mills gave the new Mk III similar characteristics. After the clamping lever was released, the igniter cord ignited. The latter burned for 4-7 s, and then an explosion occurred. Mk III hit the target only by the shock wave of the explosion. Within a radius of 2, the wave was able to kill a person. With an increase in the distance, the killer action gradually fell. The metal parts of the grenade disintegrated during the explosion into fragments, but they did not pose such a danger as the striking elements of other grenades. Thanks to this, the Mk III product could be used to fight the enemy in the trenches or in buildings with minimal risks for themselves.
It is curious that the mass of the Mk III grenade charge exceeded a number of other grenades of that time, but despite this, its combat characteristics were noticeably lower and corresponded to special requirements.
By the summer of 1918, the American industry had time to establish mass mass production of new weapons. By November of the same year, the army transferred about 5,36 million serial grenades. From November 1918 to February 1919, the customer was also shipped 7 million grenades. It should be noted that the Mk III offensive grenades were not the most widespread weapons of their kind. For example, during the same period, the number of grenades Mk I and Mk II went to tens of millions.
According to known data, before the end of the First World War, they managed to send about 170 thousand grenades Mk III to Europe. A large proportion of these items were consumed during the battles. Offensive grenades with a cardboard body were used in parallel with other weapons, creating a stream of fragments, and primarily intended for solving special problems. Not always the fighter could safely use the Mk I or Mk II grenade, and therefore specialized Mk III were used.
Mk III A1
Shortly before the end of the First World War, an order was received to create a new modification of the offensive grenade. Such weapons were put into service under the designation Mk III A1 (from 1945, the name Mk 3A1 was used). The basic requirements for weapons have not changed, but this time it was necessary to change the materials used in order to simplify production. This led to some changes in the appearance of the product, as well as to other internal equipment.
First of all, the gunsmith designers changed the material of the hull. Instead of cardboard, they suggested using less thick paper with polymer coating. The paper cylinder, covered with a high lid on top, was complemented by cast metal discs on the ends, one of which had an opening for the fuse. From the curved cover refused. Inside the case is now placed less than 200 g of TNT in the form of pressed mass or flakes.
Initially, the Mk III A1 grenade was equipped with a M6A1 type fuse. By the principle of action, it was similar to the previously used products, but differed in a “linear” layout. Inside the grenade there was a cylindrical body with a drummer and moderator. Outside, as before, there was a clamping lever fixing the drummer and a check with a ring. A retarder of such a fuse provided for the undermining of a grenade through 4-6 since the release of the lever.
In its dimensions, the new Mk III A1 was similar to the grenade of the base model, but new materials made it possible to reduce its mass. Now the serial product weighed no more than 350 g. The combat qualities, despite the design changes, remained at the same level. The upgraded grenade could have killed the enemy within 2 m, but did not threaten people at long distances.
Serial grenades were still painted black with yellow markings. Grenades were supplied in closures for 25 or 50 pieces. Separate boxes for 25 products each were intended for the supply of fuses.
By the time the United States entered the Second World War, the US Army consisted of several hand grenades, including two products of the Mk III family. At the same time, as far as we know, the new grenades, which replaced their predecessor in mass production, had become the main ones. The industry supplied the armed forces with a large number of all types of grenades. As before, the Mk III A1 were not the most massive and, in terms of their numbers, were inferior to weapons of the “traditional” type, which had a metal body.
During the war, the development of the Mk III A1 grenade was carried out by creating new fuses. The design of the grenade itself did not change. On the basis of the M6A1 product, the M6A2 and M6A4 fuses have been consistently developed with various technical or technological differences. The principles of action did not change. The response time also remained at the same level.
American troops had to work in several theaters of war, and the Mk III A1 grenades were used everywhere. As in the previous war, they were used during the battles in the trenches, during the storming of buildings or other objects. Hundreds of thousands of grenades were used up, and these weapons made a definite contribution to the victory over Nazi Germany in Africa and Western Europe, as well as over Japan in the Pacific.
Mk III A2
Already during the Second World War, the American army received a new version of the special offensive grenade - Mk III A2. According to the experience of using existing weapons, they again changed the material of the hull. In addition, we developed another version of the fuse that meets current requirements. After such refinement, the pomegranate retained the same capabilities, although it became heavier.
The grenade case of the A2 version was proposed to be made of pressed wood fiber. The explosive charge was placed in a cylindrical beaker. From above, such a body was closed by a cylindrical cover, which covered it almost half. The junction of two parts of the case could overlap with a transverse sealing paper or cardboard strip. Separate metal bottoms were absent. Hole to install the fuse was right in the extruded lid. Inside the grenade was placed 227 g of TNT.
For a new grenade developed a fuse M206. By design, it resembled the earlier M6A1, but differed in the use of other pyrotechnic materials. Due to this, the fuse did not create noise, and also did not leave behind a train of smoke. The delay of the explosion is no more than 5 seconds after the lever is reset. Subsequently, new versions of this fuse were created.
The grenade Mk III of the third modification retained the dimensions of its predecessors, but was noticeably heavier. The mass of a grenade with a fuse exceeded 430. Thus, it was the heaviest weapon in its family. The combat characteristics, despite this, remained the same. The continuous shock zone of the shock wave is 2 m. At large distances, the slaughter effect quickly fell. The body of the fiber did not form dangerous fragments that threaten both the enemy and his fighters.
Scheme grenades MK3A2. Figure Warriorlodge.com
Despite a serious redesign of the design, the grenade of the new version retained the old markings, performed with yellow paint on a black background. Heavier products Mk III A2 were supplied in closures of 30 pieces. In separate boxes were fuses M206 family.
According to known data, for some time, grenades of the A1 and A2 versions were produced in parallel, but then the first model was removed from service in favor of the second. Until the end of the war, as well as in the post-war period, American industry managed to produce several million grenades. A significant part of these products was used on the fronts. At the same time, due to the specific tactical role, grenades of the Mk III line were spent less actively than other weapons.
In April 1945, the Mk III family of hand grenades was renamed MK3. Separate modifications, respectively, received designations of the form MK3A1 and MK3A2. Over the next few months, American soldiers continued to use the renamed weapon to defeat the enemy in certain conditions.
At the time of the end of World War II, the US Army managed to create a solid supply of all types of grenades, including the offensive MK3 family. As a result, the production of such weapons lasted for some time, but was quickly stopped. In warehouses accumulated significant stocks of grenades that could be used in a future war. At the same time, some of the products were regularly used in combat training activities.
The latest version of the offensive grenade MK3 with the body, not giving striking fragments, appeared in the years of the Second World War. After this, new modifications of such weapons were not created. However, the US Army and its allies kept these grenades in service and regularly used them in various armed conflicts. Despite certain obsolescence, the MK3 remained a very convenient means for fighting the enemy in limited amounts of trenches, dugouts, firing points, etc.
During the battles and exercises, the army used up the existing stock of MK3 grenades of all major modifications. Despite this, these weapons remained available for a long time. According to some information, a significant number of such products remained in the arsenals almost until the end of the eighties. According to other sources, the MK3 grenades can still be used by some units. In the postwar period, the United States created a large number of different types of hand grenades, but direct analogues of the Mk III / MK3 were not developed. As a result, in certain circumstances, fighters may need very old items.
During the two world wars, the Mk III / MK3 offensive grenades, designed to safely attack closed structures or troops in the trenches, proved to be the best. Such weapons inflicted significant damage to the enemy, violating his defenses, and in addition, he saved his fighters from accidental wounds. It was possible to obtain such results due to the abandonment of traditional solutions in favor of unusual ideas.
FM 23-30 “Grenades and purotechnic signals”. - Department Of The Army, 1988.
TM 43-0001-47 “Army Equipment Data Sheets: Ammunition Peculiar Equipment”. - Department Of The Army, 1984.
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