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From "Deutsche Sturmgewehre bis 1945" by Peter Senich:
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In another thread (viewtopic.php?f=36&t=122572), AHF forum member Art provided a translation to English for the above article:Kosta_g wrote: ↑15 Sep 2018 12:31http://litresp.ru/chitat/ru/%D0%9F/pono ... omat-horna
Yuri Ponomaryov “The Horn’s sub-machine gun”
In the course of war in the former German Army the new type of weapon for so-called “intermediate” cartridge appeared – an automatic carbine Mkb 42(H), which was lately converted into machine-pistol MP-43 having the better accuracy of hits and combining the features of machine-pistol, self-loaded rifle and carbine with the prospect of replacing them in the future.
The appearance of MP-43 was for the most part caused by the reduction of the actual range of small-arms’ fire, by the wish to lighten the weight of the weapon and to increase the carried load of ammo, to increase the range of fire and destructive power of machine-pistol and also by the tendency to unification of weapons traditional in the former German Army.
The extremely difficult state of German economy in the years preceding the defeat of the army stimulated the creation of the cheap in production models of weapon, with the seize, weight and combat characteristics similar to MP-43 (MP-44).
The models of Weapon created in 1945 by the designers Horn and Barnitzke turned out to be extremely simple and cheap in production. The tests in troops of these models in Germany weren’t accomplished in time.
However, the Red Army troops had seized as trophy 9 Horn’s sub-machine guns (5 at Kummersdorf proving ground and 4 arrived from trophy parties, all the last having the combat damage). The overall number of produced Horn’s sub-machine guns is unknown, but apparently, this number cannot exceed several dozens. Nevertheless, these models of weapon are of interest from the point of view of design and production. One of the trophy copies was tested at the proving ground of the Chief Artillery Department of Defense Ministry.
The sub-machine guns was designed according to the 1944-45’s German Weapon Department’ specifications for the machine-pistol (in German terms) for 7,9-mm cartridge mod. 1943. Officially in German documents the intermediate cartridge is called pistol cartridge mod 43. (Pistolne-Patr. 43 mE). Along with it the designation as short cartridge mod. 43 (Kurz-Patronen 43 mE) can be frequently met in the documents. The number of arguments can be posed in the defense of both variants, but it is not the goal of the present article, so henceforth we will call this cartridge 7,9-mm cartridge mod. 43.
According the personal notes of designer Horn the basic specifications of Weapon Department were as follows:
1. The principle of blocking – loose breech (Massen-verschluss).
2. The location of the breech in cocked position: in forward position.
3. Magazine: from Mkb 42 (H) sub-machine gun.
4. Individual and serial fire.
5. Weight – 4 kg.
6. The bore length and the overall length – the same as for Mkb 42 (H) automatic carbine.
In the same specifications it was noted that this “machine-pistol” have to be better than automatic carbine in regard of reducing time and simplicity of production at the expense of wide usage of stamped details.
As it seen, the main goal of the Weapon Department’s demands was the creation of the most simple and cheap in production model of sub-machine gun for 7,9-mm cartridge mod. 43 along with preservation of good combat qualities (accuracy of individual fire, weight, length etc.).
One can see also from the aforementioned specifications that the German Weapon Department found it possible to develop the most simple and cheap design of sub-machine gun only with the use of loose breech principle, that was why the loose breech principle of blocking was mentioned in the specifications.
The loose breech principle allowing simplest weapon design, paid its way in machine-pistols for pistol cartridge, the experience of employment of which in WW2 allowed to appreciate in full measure their tactical and technical advantages. Along with good reliability of action, high rate of fire, and simplicity of manufacturing and use, machine-pistol have such drawbacks as insufficient power of fire on medium ranges, and that led Germans to the idea of necessity of the increase in cartridge power and development of sub-machine gun for more power cartridge.
The significant increase in the cartridge power when compared with pistol led to great difficulties in realization of sub-machine gun design based on the loose breech principle; as a result they lost their main mobile qualities – simplicity, small weight and linear sizes (Mkb-42(N) automatic carbine, sub-machine guns MP-43 and MP-44).
However German Weapon Department didn’t refuse from the idea of the creation of a simple in all respects sub-machine gun based on the loose-breech principle but for more powerful cartridge and in its demands it directed designers on the way of creation of such a sub-machine-gun.
The difficulties in realization of design of sub-machine gun with the overall weight of 4 kg with a loose breech which for cartridge mod. 43 had to have a weight of about 1,5 kg led Horn to the very original idea of retardation of more light breech (0,8-0,9 kg) with the gas pressure, powder gases being taken from the bullet entrance of the cartridge-chamber. The design of the sub-machine gun based on that principle was experimental and some details were completed already on the manufactured samples as it can be seen from the discrepancies in the actual details’ sizes and the sizes on the drafts.
Moreover from the personal notes of Horn it’s seen that this type of the automatic mechanism wasn’t researched by Germans using gauges registering the functioning of the mechanisms.
At the same time in all probability simultaneously with Horn a German designer Barnizke was designing self-loaded carbine for the same cartridge using the principle of retardation of the loose breechblock with gas pressure. But unlike Horn, he retarded the breech in a far later period of the shot with powder gases taken through 4 side holes in a bore at 310 mm from the breech end.
However, as tests of automatic mechanisms and fire tests of Barnitzke’s self-loaded carbine have shown that the principle of retardation of the breechblock by gas pressure in later period didn’t provide any appreciable results in reducing the weight of a loose breechblock and cannot serve as a radical method for designing a simple, reliable sub-machinegun with good combat characteristics for a cartridge of German 7,9 mm mod. 1943 type. Without any additional proofs such characteristics as the weight of the loose breechblock of about 1,4 kg and the 34% effectiveness of retardation of the breechblock by gases are the evidence of this. A rather poor accuracy of individual fire should be added, the accuracy of automatic fire being beyond any reasonable limits due to the strong hits of breechblock in forward and backward positions, since even at individual fire the carbine “picks” down after shot, and the breechblock hitting the back plate at recoil draws the barrel up. On the other hand the Horn’s principle of retardation using the powder gases taken from the bullet entrance of the cartridge-chamber enables to greatly reduce the weight of the breechblock, the effectiveness of retardation being 75 %.
The sub-machinegun of Horn’s works based the principle of the use of a power of the breechblock’s recoil.
The barrel is locked with a semi-loose breechblock which in the initial moment of movement is retarded by the gas pressure on the breechblock via a special device.
The percussion mechanism is of the cock type with a revolving cock.
The trigger mechanism enables individual and serial fire. The switch also serves as a safety lock.
The feeding is carried out from the MP-43 magazine.
The sight is fixed (300 meters, open). The peculiarity of the sight is a shape of the slit.
The overall design of Horns’ sub-machinegun bears the signs of the intention to allow the maximum number of details to be produced using the stamping. Only the barrel and the combat scutcheon require machine handling! The other details are either very simple (screws. axes, studs) or made with stamping.
The butt and the pistol handle are made from 30-mm sick board.
In order to ensure the maximum vitality of stamped constructions of the sub-machinegun and to improve the accuracy of fire the automatic mechanisms is based on the work with incomplete movement of the breechblock to the backward position.
The main combat characteristics of carbine and sub-machinegun are given in the table:
Caliber, mm/7,92 /7,92
Weight, kg/4,6 /4,7
Length of the barrel, mm/410 /410
Overall length, mm/934/930
Aiming range, m/ 800/fixed sight, 300
Feeding/ MP-43 magazine
Number of cartridges in the magazine/30/30
Practical fire rate, shots per minute/30-60/40-75
Muzzle velocity, m/sec/700/633
Length of the aiming line, mm/418/266
Rate of fire, shots per minute/-/500-550
The construction of locking and percussion-triggering mechanisms represents the greatest interest.
The bore is locked with semi-loose breechblock which when moving backwards under the action of recoil force is retarded by gas pressure on the breechblock in the direction opposite to this force.
The principle of breechblock’s retardation by gas pressure and its realization in Horn’s sub-machinegun is new and from that point of view is very interesting (in German terms Gasdruckverschluss – locking by gas pressure).
At the moment of shot after the bullet passes the bullet entrance of the cartridge chamber, the gas pressure is delivered via piston to the breechblock. Thus, the gas pressure on the breechblock in backward direction is counterbalanced by the gases’ action on the breechblock via the piston in forward direction.
However, due to the recoil force of gases is higher then force applied to the breechblock from the piston in sum with other counteraction forces the breechblock moves back. As result the breechblock overcomes the movement of the piston, making it go down.
As soon as the upper plate “a” of the piston (see the scheme on page 23) reaches the level of the surface “b” of the breechblock, the latter will loose cohesion with the piston. However, the action of the piston on the breechblock won’t end, but will greatly decrease, since instead of directly delivering pressure on the breechblock, the latter will be retarded by gas pressure via the friction force between the plate “a” and the breechblock’s surface “b”.
After the pressure in the bore falls, the piston’s spring will hold the piston in the lower position in order not to block the breechblock during the movement in forward direction.
When the breechblocks returns in the initial position it touches the piston’s head at lifts the piston in the upper position.
The percussion-triggering mechanism is of the cock type with a revolving cock. The triggering mechanism enables both individual and automatic fire, for this the switch is present which simultaneously serves as a safety lock preventing the shot at incidental pressure on the trigger.
The percussion-triggering mechanisms includes the following principal details (see the scheme): a trigger (1), a trigger lever (2), a cock (3), an automatic trigger (4), a trigger pawl (5), the switch (6), a switch lever (7), a switch crosspiece (8), a percussion spring (9), a spring of the trigger lever and the counterbounce (10), a spring of the automatic trigger and the trigger pawl (11), a counterbounce (12).
At individual fire the trigger is in the medium position marked by letter “E” (Einzelfeur” – individual fire). In this case (see position “A”) at pressure on the trigger (1), its forward part acts on the “a” end of the trigger lever (2), as a result the latter moves back and releases the cocking notch “b”. Since the automatic trigger (4) is pressed forward by the breechblock and the trigger pawl (5) is set against the forward side of the cocking notch of the cock, the last has an opportunity to turn under the action of the spring and to hit the firing pin.
When the breechblocks cocks the gun the cocking notch turns slightly higher than the upper surface of the triggering pawl, as a result the latter under the action of the spring (11) turns up to the stop, and consequently the cocking notch of the cock stops on the upper surface of the cocking pawl (see position “B”). When the trigger is released, the triggering lever is moved forward by the spring (10) and turns the cocking pawl by the forward end, the cocking notch of the cock moves from the latter on the cocking lever and mechanism is set in the initial position “A” before the shot.
To enable the serial fire one needs set the switch (6) in the position marked by the letter “D” (Daeurfeuer – serial fire). The switch lever moves back and turns with the bent “г” the trigger pawl by the lug “д” (see position B). As a result when the trigger is pressed, the cock will be released in the same way as at individual fire.
However, when the cock is raised by the breechblock, the trigger pawl cannot stand under the cocking notch as it is held with the switch lever. In this case the cocking notch is stopped by the sear of the automatic trigger which tries to turn back under the action of the spring (11).
When the breechblocks reaches the forward position it presses the arm “д” of the automatic trigger forward so the cocking notch is released and the cock is able to turn.
When the trigger is released in order to cease fire the triggering lever is moved forward by the spring (10) and blocks the movement of the cock so it stops in the initial position before the shot “B”.
The switch (6) simultaneously serves as a safety lock, it should be set in the position marked by the letter “s” (Sicher – safe).
Here its crosspiece “e” is set against the back lug of the lateral sides of the cock, as a result the cock is blocked.
The counterbounce serves to fix the breechblock in forward position not allowing it to move back as a result of a hit.
In the Horn’s sub-machinegun the counterbounce is very important, because without it the shot without the breechblock being retarded by the piston or the shot at insufficient cohesion of piston’s and breechblock’s surfaces may occur.
The shot without retardation of the breechblock is very undesirable since in this case the loose and relatively light breechblock recoils back with high velocity (10-13 m/sec). In this case several hits of the breechblock on the back plate disrupt the latter.
The function of the counterbounce is to block the breechblock in the forward position from behind with the arm “K” and not to allow it to move back until the cock hits the firing pin. At the moment of the hit the cock presses the upper surface of the counterbounce down and turns it as a result the breechblock is unlocked.
When the sub-machinegun is loaded by hand the breechblock is not hold by the counterbounce too, as when the trigger is loose the triggering lever is in the forward position pressing the arm “H” of the counterbounce with the lug “M” and turning the counterbounce off.
The counterbounce is turned on by the forward end of the spring (10) which tries to lift the counterbounce’s arm “K” up. The backward en of the spring (10) is clutched between the axle of the trigger and the lug “O” of the triggering lever tries to move the triggering lever forward and its shank presses the trigger to the forward side of the cut in the body.
The reliability if the automatic mechanism was tested with the fire in different conditions of exploitation with 30 individual and 30 serial shots at each test.
The tests were conducted under the following conditions:
1. The details of the automatic mechanism were lubricated normally: the cartridges were dry, lubricated and heated up to 60 C.
2. The details of automatic mechanism were normally, the shots were fired under the elevation and declination angles up to 90 (0) and in dusty conditions.
3. The details of automatic mechanism were densely lubricated: the guns and the cartridges were frozen down to – 50 degrees.
4. The details of automatic mechanism were dry (washed with gasoline): the shots were made in dusty conditions and without dust.
In all kinds of tests 1900 shots were made, as a result no break caused by automatic mechanism was registered (this result not always can be achieved by modern Kalashnikov’s sub-machinegun).
The good reliability of the automatic action under different conditions of exploitation is explained by the automatic mechanism being insensible to the incomplete recoil of th4 breechblock due to the relatively high value of breechblock’s movement behind the next cartridge in the magazine (125 mm), the small friction surface of the breechblock and relatively large slit between the breechblock and the body.
The accuracy of fire with individual shots from lying position at different ranges in comparison with MP-43 is given in the table (r50 – centimeters)
Model/100 meters, 300 meters, 600 meters
In the process of tests of the sub-machinegun the following exploitation shortcomings were revealed:
1.The sub-machinegun is uncomfortable to carry in hands due to large lateral sizes and poor position of the center of mass.
2.During crawl the gun is uncomfortable due to the protrusions on the reloading handle projected to both sides.
3.In lying position cocking the gun is very uncomfortable due to the reloading handle being too far forward.
4.The aiming is uncomfortable due to too short and thin butt (made of 300-mm sick board)
5.The butt is attached to the body not rigidly enough, owing to this the butt swings strongly.
6.The design of the latch of the magazine in the mouth of the body doesn’t ensure stability of its work; owing to this the magazine is frequently stuck when one tries to detach it.
7.The position of the fire switch on the left side is uncomfortable at aiming fire as one should remove the left hand from the gun to switch fire.
All the aforementioned shortcomings represented the teething troubles, because the sub-machinegun didn’t undergo tests in troops, which would lead to most of the problems being fixed.
In general Horn managed to fulfill perfectly the posed task, creating quite the viable model of weapon. And only the capitulation of Germany prevented the mass production of his sub-machinegun.
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