Abstract:
The mechanism is applicable in military manufacture and is designed to be built in automatic and semi-automatic firearms of the kinds: pistols, machine guns and submachine guns. This mechanism is with simple construction and ensures enhanced over travel security for weapons, no safety, allowing for no accidental shooting to take place. The striker-trigger mechanism consists of a striker mechanism, a trigger mechanism and a fire-selecting mechanism integrated via a rear block ( 30 ). The fire selecting mechanism takes the form of a fire select ( 29 ). placed behind the breach block ( 34 ) with an extractor, and an internal step-like channel ( 7 ) centrally located, containing a firing pin ( 1 ) with enlargements at both ends, front and rear one respectively. The firing pin ( 1 ) has profile tooth ( 2 ) protruding outside the breach block ( 34 ) meant to engage with the trigger mechanism through a trigger ( 15 ) equipped with a return spring ( 18 ) and joint-lined to the frame ( 35 ). The trigger ( 15 ) connects with a profile one-arm lever, made as trigger bar ( 10 ) pushed to the breach block ( 34 ) by spring ( 19 ). The trigger bar ( 10 ) has an upper lug surface ( 11 ) and a firing tooth ( 12 ) to link with the striking mechanism. Between the two enlargements two axially movable spring cups ( 3  and  5 ) are separated by the volute firing pin spring ( 4 ) coiled around the firing pin ( 1 ).

Description:
FIELD OF THE INVENTION 
     This self-loading striker-trigger mechanism is meant to be built in automatic and semi-automatic firearms of the kinds: pistols, machine guns and submachine guns for automatic and semi-automatic fire. 
     BACKGROUND OF THE INVENTION 
     Known striker-trigger mechanisms for building in handguns fall into two major types: 
     The first type are striker-trigger mechanisms with a striker. This type of striker-trigger mechanisms involve a hammer mechanism coupled with a trigger mechanism. The hammer mechanism includes a striker interacting with a firing pin spring. Under the impact of the firing pin spring the striker rotates to hit a firing pin (a prolate pin-shaped body), which flies ahead and hits the (primer) capsule of a cartridge in the chamber and executes a shot. 
     This type of striker-trigger mechanisms come with two kinds of trigger mechanisms—for single— and double-action modes of operation respectively. 
     With the single-action trigger mechanisms after loading the weapon, that is feeding a cartridge in the chamber of the barrel, the striker can be manually lowered without producing a shot and then manually set into combat position right before the firing. 
     The double-action trigger mechanisms of the above referred type are applicable in submachine and machine guns. With them the combat position of the striker is achieved through pressing the trigger. 
     With the submachine guns this known striker-trigger mechanism employs a device for shot separation and safety tools. 
     With the machine firearms there is also a fire selecting mechanism for automatic and semi-automatic fire. 
     The weaknesses of this traditional type of striker-trigger mechanisms are: 
     With the single-action striker-trigger mechanisms to carry the gun in a ready-to-fire state after loading it, the striker has to be manually dropped without firing; and later right before shooting to be manually set into firing position, all of which takes time. 
     With the double-action striker-trigger mechanisms the striking hammer is put into firing position by means of pulling the trigger. The first shot, then, requires prolonged and heavy motion of trigger, unlike second and subsequent shots fired by brisk and smooth trigger motion. That forces the user into getting accustomed to two kinds of trigger motions—the long and heavy one causes deviation and accuracy reduction. 
     The second type is a single-action striker-trigger mechanism employing a firing pin in direct link with a firing pin spring, which is either coiled around it or placed behind it. In this kind of striker-trigger mechanisms the firing pin gets into combat position, firing pin spring cocked, simultaneously with loading the gun, i.e. with issuing a cartridge into the chamber. 
     A shortcoming of this known type of mechanism is that carrying the gun ready-to-fire, the spring is exerted all the time, which leads to its fatigue over time, while a major requirement for modern firearms in military or law-enforcement use, is to allow to be carried for a long time without depreciation being caused to their mechanics. 
     TECHNICAL SUMARY OF THE INVENTION 
     The invention aims at devising a self-loading striker-trigger mechanism for semi-automatic and automatic fire featuring simple construction and enhanced security upon carrying the firearms loaded no safety, capable of eliminating any possibility of accidental discharge, and with the trigger motion smooth and equally long for each shot in automatic or semi-automatic fire modes. 
     The solution to the task is a self-loading striker-trigger mechanism for machine guns and submachine guns, which consists of a striker mechanism, trigger mechanism and a fire selecting mechanism for switching from automatic to semi-automatic fire. The striker mechanism includes a firing pin fixed in a breach block mounted in the upper rear end of the frame of the firearm. The firing pin has a pointed front end with a firing pin spring coiled around it. The trigger mechanism mounted below has a trigger to set firing pin into combat position. As per this invention the striker mechanism, the trigger mechanism and the fire selecting mechanism have been put together in a single unit in the form of a rear block. The fire selecting mechanism is accomplished as a fire select placed in the rear part of the frame. Inside the rear central part of the breach block longitudinally a step-like channel has been run to house the firing pin fitted with a profile tooth, designed to mesh with the trigger mechanism, whose trigger is equipped with a spring to push the trigger back. The trigger is joint-linked to the frame. Again joint-linked to the trigger comes a profile one-arm lever in the form of a trigger bar, pressed to the breach block by another spring. The trigger bar has a contact firing tooth with the striking mechanism, coming as an upper lug sideways to the trigger bar. 
     Optionally the self-loading striker-trigger mechanism for machine and submachine firearms, as per this invention, can be realized with the striker mechanism having enlargements at both ends—front and rear enlargements respectively. The lower end of the rear enlargement has the profile tooth engaging with the firing tooth on the trigger mechanism. Both teeth&#39;s profiles correspond. Central to the front enlargement of the firing pin is its front pointed end. Between the two enlargements two axially moving spring cups are positioned with external diameters more and internal diameters less than the external diameter of the enlargements, so that their axial movement is restricted by them. The two axially moving cups are separated by the volute firing pin spring coiled around the firing pin, which has a diameter less than the external diameters of the cups, hence holding the cups within their allocated enlargements. The striking mechanism thus shaped as a unit is mounted, along the same axis as the gun&#39;s barrel, in the step-like lidded channel in the rear central area of the breach block, with front and rear props to space the axial movement of the movable cups. 
     Another optional realization of the self-loading striker-trigger mechanism for machine and submachine firearms, as per this invention, features a lengthwise cut-out in the lower rear part of the step-like channel of the breach block, parallel to its longitudinal axis, holding the profile tooth to the rear enlargement of the firing pin so that it protrudes outside the longitudinal cut-out. The step-like channel is constricted in its front part and shapes a step-like tightening, whose foremost surface is the front prop for the spring cup in extreme foremost position. The front part of the step-like aperture has minimal diameter for the front pointed end of the firing pin to come in; while in its rear part, maximal in diameter, rests stationary the rear prop for the movable cup in the form of sleeve. In the longitudinal cut-out area the sleeve has a lengthwise fuller as wide as the longitudinal cut-out in the step-like channel and fitting so that the tooth of the firing pin be able to move freely along its longitudinal axis. Sleeve&#39;s outside diameter equals the diameter of the rearmost, widest part of the step-like channel, while the inside diameter of the sleeve is a little larger than the rear enlargement of the firing pin, so that it can move freely along and the firing pin can move unhindered along the axis. 
     A possible realization under this invention of the self-loading striker-trigger mechanism for machine and submachine firearms works with the sleeve stationary—fixed in the rear part of the step-like channel in the breach block by means of a fixing tooth. 
     A possible realization under this invention of the self-loading striker-trigger mechanism for machine and submachine firearms optionally has the firing pin tooth with a flat front surface/area square to the axis of the firing pin and rear surface/area slanting to this axis; while the firing tooth is with flat rear surface, also square to the axis of the firing pin and slanting front surface corresponding with the slanting surface of the firing pin tooth. 
     Another option for realization of the self-loading striker-trigger mechanism for machine and submachine firearms works with the spring of the trigger mechanism, made of spring wire, around a stationary axle mounted to the rear block. One arm of this spring presses the lower part of the trigger bar, parallel to the axis of the firing pin, to fall within a longitudinal groove made there for it; and below the second arm of the spring there is a support, part of the rear block, parallel to the axis of the firing pin, so that the spring presses the trigger bar upwards to the inside of a ramp-channel with slanting rear surface made in the lower rear part of the breach block, parallel to the axis of the firing pin. 
     The self-loading striker-trigger mechanism for machine and submachine firearms under the object of this invention can be realized with the trigger i suspending from an axle attached to the frame and passing through a canal made in its upper part. The front foremost surface of the above mentioned upper part upholds the helical spring for trigger return, coiled around the axle. The upper part of the trigger has a second axle set up, which fits with the trigger bar in a bearing in the upper rear part, where the arcuated lug lies and the firing tooth situated in the rearmost surface of the trigger bar. The trigger bar will have to employ a tooth to be spring-retained—spring provided in the rear block. 
     The self-loading striker-trigger mechanism for machine and submachine firearms, as per this invention, would preferrably be accomplished so that the rear block is positioned in the upper rear part of the frame having the fire select connected by means of an arm with tilting inside surface propping the upper bent end of the spring retention, whose second end fits in a cut-out in the rear part of the rear block. The arm of the fire select fits (bearing) with a stationary axle in the rearmost part of the frame and is in contact with a fixing pin and a spring. 
     The advantages of the self-loading striker-trigger mechanism as proposed by this invention will be as follows: 
     This mechanism features a simple structure and its operation disnecessitates the safety as unintentional shots are prevented from going off, eliminated by the design of the striker and trigger mechanisms engaging through their teeth with matching profiles. 
     Also advantageous is the possibility to carry the gun loaded, since the firing pin spring is cocked directly and only by pulling the trigger. No less a contribution to the existing level of technology in terms of facilitated utilization, is the fact that the self-loading striker-trigger mechanism&#39;s configuration implies rectilinear movements of the trigger, smooth and equally long for all shots. Accidental discharge is impossible with it, since the the firing tooth of the trigger bar within the trigger mechanism is positioned before the tooth of the firing pin, hence functions as safety. Thus a shot cannot be fired. 
    
    
     BRIEF DESCRIPTION OF THE DROWINGS 
     An example of an optional realization of the self-loading striker-trigger mechanism, as per this invention is demonstrated in the figures supplemented, of which: 
     FIG. 1 represents a vertical section view of a gun with a self-loading striker-trigger mechanism, stationary. 
     FIG. 2 gives a side view of a machine firearm with a partial section through the self-loading striker-trigger mechanism with trigger pulled to its aftermost position immediately before a shot will be fired. 
     FIG. 3 illustrates a partial vertical section of part of the machine firegun through the self-loading striker-trigger mechanism while firing a shot. 
     FIG. 4 gives a side view of the machine gun with a partial vertical section through the self-loading striker-trigger mechanism the instant after a shot has been fired. 
     FIG. 5 is a partial vertical section of part of the machine gun through the self-loading striker-trigger mechanism in moving the breach block ahead with a new cartridge fed in. 
     FIG. 6 shows a partial vertical section of part of the machine gun through the self-loading striker-trigger mechanism in foremost front position of the breach block the moment an automatic shot is being fired, trigger pulled. 
     FIG. 7 represents a partial vertical section of part of the machine gun through the self-loading striker-trigger mechanism at the moment of reloading in semi-automatic fire mode. 
     FIG. 8 is a partial vertical section of part of the machine gun through the self-loading striker-trigger mechanism after reloading in combat position. 
     FIG.  9 /A represents a view from above of the fire select in upper position of device in automatic fire mode. 
     FIG.  9 /B is a right-hand side view of the fire select mechanism in upper position of device in automatic fire mode. 
     FIG.  9 /C shows a back view of the fire select mechanism in upper position of device in automatic fire mode. 
     FIG.  9 /D is a left-hand view of the fire select mechanism in upper position of device in automatic fire mode. 
     FIG.  10 /A represents a view from above of the fire select in lower position of device in semi-automatic fire mode. 
     FIG.  10 /B is a right-hand side view of the fire select mechanism in lower position of device in semi-automatic fire mode. 
     FIG.  10 /C shows a back view of the fire select mechanism in lower position of device in semi-automatic fire mode. 
     FIG.  10 /D is a left-hand view of the fire select mechanism in lower position of device in semi-automatic fire mode. 
     FIG. 11 displays a horizontal section through the breach block showing the channel of the self-loading striker-trigger mechanism. 
     FIG. 12 is a view from above, breach block disassembled, with a trigger mechanism set up in the frame. 
     FIG. 13 illustrates an overview of the machine gun with a fragmentary section through the self-loading striker-trigger mechanism. 
     FIG.  14 /A displays a vertical section of the striker mechanism in position setting the firing pin in combat readiness. 
     FIG.  14 /B represents a vertical section of the striker mechanism in position operating the firing pin for executing a shot. 
     FIG.  14 /C is a vertical section of the striker mechanism in position returning the firing pin in initial stationary state. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 displays a vertical section of a machine gun, mechanisms stationary, with a built-in self-loading striker-trigger mechanism, as put forward by this invention. Pistol represented machine firing gun consists of a frame  35 , to the front of which a barrel  36  is located whose rear end shapes into a cartridge chamber for a cartridge  48  to be fed. Under the barrel  36 , in the front part of the frame  35  a helical recoil spring  38  is mounted, coiled around axle  39 , at the rear end of which is the pistol dissasembly latch  42 . Behind the disassembly latch  42  is the slide lock  37  for the barrel  36 , below which is positioned the trigger mechanism linked with a striker mechanism, located backward up in the breach block  34 , under which within the frame is the magazine  40  and a magazine lock  41  releasing the magazine  40 . Up on the breach block  34  come front  46  and rear  47  sights respectively. 
     The self-loading striker-trigger mechanism, as per this invention, consists of the kinematically connected one to the other a linking unit accomplished as a rear block  30 , striker mechanism, mounted in a breach block  34 , trigger mechanism and fire select mechanism in the form of fire select  29  of either automatic or semi-automatic fire mode. The fire select  29  is situated in the rearmost part of the frame  35 . 
     The breach block  34  is installed in the upper part of the frame  35 . To the front right-hand part of the breach block  34  an extractor  43  is attached in the form of a two-arm lever with bending front end of one of its arms, leaning on the front foremost surface of the breach block  34 . The extractor  43  (shown in FIG. 11) is joint-linked to a stationary axle  44 , with the rear end of the second arm of the lever, representing extractor  43  with fastened helical spring  45 , running within a channel square to axis  44 . 
     The self-loading trigger mechanism is placed along the axis of the barrel  36 , as displayed in FIGS. 1,  14 /A,  14 /B and  14 /C, and consists of a firing pin  1  with enlargements at both ends, that is rear enlargement  1 a and front enlargement  1   b , and a tooth  2  constructed to the lower end of the rear enlargement  1   a  to mesh the firing pin  1  with the trigger mechanism. Tooth  2  has a flat front foremost surface square to the axis of the firing pin  1  and slantwise to the same axis rear surface. In the front part of the firing pin  1 , central to the front enlargement comes a pointed end  1   c . Between the two enlargements  1   a  and  1   b  two axially movable spring cups  3  and  5  are placed, whose internal diameter is less than the external diameter of the enlargements  1   a  and  1   b , so that their movement along the axis is restricted by them. The two axially movable spring cups  3  and  5  are separated by a volute firing pin spring  4  around the firing pin  1 , pressing cups  3  and  5  to their adjacent enlargements  1   a  and  1   b  respectively. 
     The step-like channel  7  within the breach block  34  has a lengthwise cut-out  7   a , made to its lower rear part and parallel to its longitudinal axis. This lengthwise cut-out  7   a  takes the tooth  2  of the rear enlargement  1   a  of the firing pin  1 , and tooth  2  is positioned so that it can protrude outside the lengthwise cut-out  7   a . The front part of the step-like channel  7  is constricted into a step-like tightening  7   b , whose front part is least in diameter and ends in aperture  7   b  for the front pointed end  1   c  of the firing pin  1  to pass through. Behind the rear axially movable cup  3 , in the rear largest in diameter part of the step-like channel  7  of the breach block  34  a spacer sleeve  6  is placed to prop movable spring cup  3  upon setting the firing pin  1  into combat position (FIG.  14 /A). Sleever  6  has a longitudinal fuller  6   a , made in the area of the longitudinal cut-out  7   a  in the rear part of the step-like channel  7 , accomplished within the breach block  34  and fitting so with it that the tooth  2  of the firing pin  1  can move freely parallel to the longitudinal axis. Sleeve  6 &#39;s external diameter is equal to the diameter of the rear, widest part of the step-like channel  7 , and the internal diameter of this sleeve  6  is a little larger than the rear enlargement  1   a  of the firing pin  1 , so that it goes freely through it and the firing pin  1  can move unhindered along the axis. Spacer sleeve  6  is stationary—attached to the rear part of the step-like channel  7  in the breach block  34  by means of a fixing tooth  6   b.    
     A lid  8  has been provided in the rear part of the breach block  34  to cover the step-like channel  7  and hence the striker mechanism is contained within it. 
     The trigger mechanism, demonstrated in FIGS. 1 and 12, consists of trigger  15  suspending from axle  17 , fixed to the frame  35  and going through channel  16 , made in the upper part of the trigger  15 . A volute spring  18  to retain the trigger  15  coiled around axle  17  leans on the rearmost surface of the above referred upper part. Axle  14  is mounted to the upper part of the trigger  15  joint-linked with trigger bar  10  in the form of a profile one-arm lever. The upper rear part of the trigger bar  10  has an arcuated lug  11 . The rear aftermost part of the trigger bar  10  in the top has a firing tooth  12  made to engage with tooth  2  of the firing pin  1 . The firing tooth  12  has a rear aftermost surface square to the axis of the firing pin  1  and a front slanting surface corresponding with the slanting surface of tooth  2  of the firing pin  1 . 
     The rearmost surface of the trigger bar  10 , in the area below the firing tooth  12  there is a tooth  13  to hold the trigger bar  10  in down position in semi-automatic fire mode and with trigger  15  tightly pulled, which takes place via a lamellar retention spring  23  mounted in the cut-out  32  made in the rear block  30 . The rear block  30  is located in the rear upper part of the frame  35  and serves to connect the striker and the trigger mechanisms with the fire select mechanism  29  for switching from and to automatic and semi-automatic fire modes. This fire select  29  has an arm  25  with slanting inner surface  26  and attached to axle  24 , joint-linked in an aperture in the aftermost part of the frame  35 . An upper pitch-bent end of the retention spring  23  leans on the inner slanting surface  26 , and the second end of the spring retention  23  is installed in cut-out  32  in the rear block  30 . The lower part of the trigger bar  10  parallel to the axis of the firing pin  1 , has a longitudinal canal  20  to contain one of the arms of a spring  19  coiled around a stationary axle  22 . Under the second arm of spring  19  there is a prop  21  from the frame  35  parallel to the firing pin  1 &#39;s axis. Spring  19  is meant to push lug  11  from the trigger bar  10  upwards to the inner surface of the ramp-channel  9  with rear slanting surface  9   a , which is accomplished in the lower rear part of the breach block  34 , parallel to the axis of the firing pin  1 . 
     Fire select  29  (shown in FIGS. 9 and 14) for automatic and semi-automatic fire modes is provided with a fixing pin  27  and spring  28 , in their turn meant to retain its positions in automatic and semi-automatic fire modes respectively. The rear block  30  has a repeller  33  facing front. 
     Operation of a Firearm with Built-in self-loading Strikers-trigger Mechanism Explicated 
     A machine gun with built-in self-loading striker-trigger mechanism, as provided by this invention, is loaded by means of manually sliding the breach block  34  into aftermost position and its subsequent releasing to go ahead, thus feeding the rear end of barrel  36  with a cartridge  48 . 
     Then the trigger  15  is pulled, upon which a shot is executed. Under the blow-back (recoil) action of the shot fired the breach block  34  flies ahead ejaculating the case of the fired cartridge  48  through extractor  43 . Pushed by the return spring  38 , the breach block  34  goes back to fore and selects another cartridge  48  from magazine  40  to feed into barrel  36 . 
     The stationary machine gun mechanisms shown in FIG. 1 render the firing tooth  12  of the trigger bar  10  of the trigger mechanism in position in front of the firing pin  1  tooth  2 , thus performing the role of a safety device. In such a case shot cannot be fired. 
     FIGS. 1 and 13 demonstrate the firing pin spring  4  of the firing pin  1  simultaneously pressing on the rear axially movable spring cup  3  to go backward and the front axially movable spring cup  5  to go forward. So the rear axially movable cup  3  leans on the front foremost surface of sleeve  6 , and the front axially movable cup  5  leans on the rear aftermost surface of the step-like tightening  7   b  within the step-like channel  7  of the breach block  34 . Thus the two cups,  3  and  5  respectively, press the rear enlargement  1   a  of the firing pin  1  backward, and the front enlargement  1   b  forward, putting it in this way into a stationary position. 
     To set the machine gun into automatic fire mode the fire select  29  has to be put in upper position, as displayed in FIGS.  9 /A,  9 /B,  9 /C and  9 /D. By pulling the trigger  15 , the trigger bar  10  moves backward while pressing tooth  2  of the firing pin  1  via its firing tooth  12 , thus setting the firing pin into combat position, as in FIGS.  2  and  14 /A. 
     Setting the firing pin  1  into combat position, its front enlargement  1   b  drags the front axially movable cup  5 , which presses the firing pin spring  4  and exerts it, pushing it to the leaning on the sleeve  6  rear axially movable cup  3 . The firing pin spring  4  cocks until the front end of the arcuated lug  11  of the trigger bar  10 , which is moving in the ramp-channel  9  of the breach block  34 , slides into the slanting inner rear surface  9   a  of this ramp-channel  9 ; the sliding makes the trigger bar  10  fall downward and the firing pin tooth  12  releases the profile tooth  2  of the firing pin  1 , which under the pressure of the firing pin spring  4  flies forward, as seen in FIG.  3 . 
     Firing pin  1  moving forward by force of the fully cocked firing pin spring  4 , it presses on the front spring cup  5 , which leans on the front step-like enlargement  1   b  of the firing pin  1 , thus moving it forward. The front movable cup  5  stops moving along the axis when leaned on the rear aftermost surface of the step-like tightening  7   b  of channel  7  in the breach block  34 . At that the firing pin  1  keeps advancing by inertia. In the last stage of its movement the firing pin  1 , via its rear enlargement  1   a  drags the rear axially movable cup  3  and so partially cocks the firing pin spring  4 . That is the moment of firing a shot, represented in FIGS.  3  and  14 /B. At that point the front enlargement  1   b  of the firing pin  1  is leaning on the step of the tightening  7   c  of channel  7  and the front pointed end of the firing pin  1  protrudes from the aperture  7   b , so that to strike on the primer of the cartridge  48  chambered in the barrel  36 . 
     The firing pin spring  4 , partially cocked, by the impact of the force produced upon its forward contraction, by the inertia of the firing pin  1  moving, presses on the rear axially movable cup  3  backward and moves it to the front foremost surface of sleeve  6 , thus returning the firing pin  1  into its initial position, shown in FIG.  14 /C and above described as stationary. 
     After the shot is fired, under the blow-back action of the recoil, the breach block  34  flies backward ejaculating the case of the cartridge shot  48  through the extractor  43 . The breach block  34  moving backward, the ramp-channel  9  is positioned above the arcuated lug  11  of the trigger bar  10 , which under impact of spring  19  is elevated. On its way back tooth  2  of the firing pin  1  slides on its rear slanting surface down the reversely slanting surface of the firing pin tooth  12  of the trigger bar  10  and leaps over it with the firing pin  1  sustaining its movement back together with the breach block  34 , as shown in in FIG.  4 . This movement continues until the breach block  34  reaches its aftermost rear position. 
     Then, under the impact of the recoil spring  38 , the breach block  34  starts forward picking another cartridge  48  from the magazine  40  on its way and feeding it into the chamber of the barrel  36 . Upon this advance of the breach block  34  the tooth  2  of the firing pin  1  catches the firing tooth  12  of the trigger bar  10  thus blocking the movement of the firing pin  1  into halt. The breach block  34  keeps moving ahead, cocking the firing pin spring  4 , which contracts, as shown in FIG.  5 . This contraction of the firing pin spring continues until the inner slanting surface  9   a  of the ramp-channel  9  leans on the arcuated lug  11  of the trigger bar  10  pressing it downward. Thus the firing tooth  12  of the trigger bar  10  releases the profile tooth  2  of the firing pin  1  and that flies ahead under impact from the firing pin spring  4 ; in the final stage of its way it drags the axially movable cup  3 , partially cocking the firing spring  4  at that, contracting it until the front pointed end  1   c  of the firing pin  1  hits the primer of the cartridge  48 , upon which a shot is fired (demonstrated in FIG.  6 ). 
     At the point of releasing the firing pin  1  the breach block has reached its foremost front position, shown in FIG.  6 . 
     The blow-back (recoil) action after shooting causes the breach block  34  again to fly backward ejecting the case (FIG.  4 ). 
     The above described sequentially repeats until the trigger  15  is relieved. Then, the trigger  15  released, the breach block  34  resumes its foremost front position, but the slanting surface  9 a of the ramp-channel does not reach the arcuated lug  11  of the trigger bar  10  and does not press it downward. So the lug  11 , under impact of spring  19  remains elevated, hence the firing tooth  12  of the trigger bar  10  and the tooth  2  of the firing pin  1  remain engaged and the automatic fire ceases. This coincides with the stationary position shown in FIG.  1 . 
     Pressing the trigger  15  again, as displayed in FIG. 2, the automatic fire proceeds until the trigger  15  is released again. 
     For semi-automatic mode of operation of the machine firearm the fire select  29  is lowered, as seen in FIGS.  10 /A,  10 /B,  10 /C and  10 /D. Hence the recoil spring  23  hinders the way of tooth  13  for retaining the trigger bar  10  in lower position. 
     Pulling the trigger  15 , the trigger bar  10  moves together with it backward and drags the firing pin  1 , because the firing tooth  12  of the trigger bar  10  is meshed in the tooth  2  of the firing pin and via the front axially movable cup  5  contracts the firing pin spring until the arcuated lug  11 , moving along the ramp-channel  9  of the breach block  34  slides into its inner slanting surface  9   a , thus causing the trigger bar to drop downward. At that the firing tooth  12  of the trigger bar  10  releases the firing pin, as shown in FIG.  2  and that under impact of the firing pin spring  4  flies ahead, to drag in the final stage of its way the rear movable cup  3  and partially exerts the firing pin spring  4  contracting it until the front pointed end  1   c  of the firing pin  1  hits the primer of the cartridge  48 . Thus a shot is fired and that is seen in FIG.  3 . 
     The blow-back (recoil) action after executing a shot causes the breach block  34  to fly backward, extractor  43  dispensing of the case. At that point the firing pin  4 , via the rear movable cup  3  returns the firing pin into its initial position. Simultaneously the breach block  34 , under impact of the return spring  38 , located in the area below the barrel  36  resumes its starting position ahead, picking another cartridge  48  on its way from the magazine  40  and feeding that into the barrel  36 . Upon that movement ahead of the breach block  34 , the firing tooth  12  of the trigger bar  10  does not engage with tooth  2  of the firing pin  1 , as the trigger bar  10  remains in its lower position locked by the meshing of tooth  13  of this trigger bar  10  and the recoil spring  23 , as shown in FIGS. 7 and 8. 
     To produce another shot the trigger  15  has to be released, and under impact of spring  18  for trigger  15  return, get back into front foremost position, on its way the firing tooth  12  of the trigger bar  10  slides on its rear slanting surface into the reversely slanting respective surface of tooth  2  of the firing pin  1 , thus leaping over and in front of it and again resuming initial combat position—demonstrated in FIG.  8 . All the time the spring  19  is pressing the trigger bar  10  upward to the lower surface of the firing pin  1 . 
     For subsequent shooting the trigger  15  has again to be pressed, as seen in FIG. 2, with the entire above described sequence repeated. 
     List of Positions from Supplemented Drawings 
       1 . Firing pin 
       1 A. rear enlargement of the firing pin  1   
       1 B. front enlargement of the firing pin  1   
       1 C. pointed end of the firing pin  1   
       2 . Firing pin  1  tooth 
       3 . Rear spring cup 
       4 . Firing pin spring 
       5 . Front spring cup 
       6 . Spacer sleeve 
       6 A. lengthwise fuller of sleeve  6   
       6 B. fixing tooth/pin of sleeve  6   
       7 . Step-like channel 
       7 A. longitudinal cut-out of the step-like channel  7   
       7 B. front aperture of the step-like channel  7   
       7 C. step-like tightening of the step-like channel  7   
       8 . Lid covering the step-like channel  7   
       9 . Ramp-channel 
       9 A. slanting surface of the ramp-channel  9   
       10 . Trigger bar 
       11 . arcuated lug of the trigger bar  10   
       12 . firing tooth of the trigger bar  10   
       13 . retention tooth of the trigger bar  10   
       14 . axle for joint-linking the trigger bar  10  to the trigger  15   
       15  Trigger 
       16 . trigger axle canal  15   
       17 . trigger  15  axle 
       18 . trigger  15  return spring 
       19 . trigger bar  10  impact spring 
       20 . trigger bar  10  groove for spring  19   
       21 . Lower spring  19  prop 
       22 . Spring  19  axle 
       23 . Trigger bar  10  retention spring for semi-automatic fire 
       24 . Fire select  29  axle 
       25 . Fire select  29  arm 
       26 . Inner slanting surface of fire select  29   
       27 . Fire select  29  fixing pin 
       28 . Fixing pin  27  spring 
       29 . Fire select 
       30 . Rear block 
       31 . Rear block  30  fixing pin 
       32 . Spring retention  23  groove 
       33 . Repeller 
       34 . Breach block 
       35 . Machine firearm frame 
       36 . Chambered barrel 
       37 .Sliding barrel  36  lock 
       38 . Recoil spring 
       39 . Recoil spring  38  axle 
       40 . Magazine 
       41  Magazine  40  catch 
       42 . Pistol disassembly lock 
       43 . Extractor 
       44 . Extractor  43  axle 
       45 . Extractor  43  axle 
       46 . Front sight 
       47 . Rear sight 
       48 . Cartridge