Abstract:
A gas operated semi-automatic rifle is disclosed having a forwardly moving gas piston located under the discharge end of a barrel. The gas piston is connected to a locking mechanism. The locking mechanism is engaged with a breechblock. As the gas piston moves a short distance forward after a round has been fired from the rifle, the locking mechanism moves rearward and disengages from the breechblock. The breechblock is biased rearward by being disengaged from the locking mechanism. The breechblock strips a new cartridge from a magazine, and reloads the rifle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Application 60/721,679, filed Sep. 30, 2005. 

   BACKGROUND OF INVENTION 
   The present invention relates to a gas operated semi-automatic rifle having a forwardly moving gas piston which allows a breechblock of the rifle to not pass totally beyond a cartridge magazine to load a new cartridge. 
   Currently most semi-automatic rifles are gas operated, with expanding gases in the rifle barrel developed by the firing of a cartridge causing a gas piston/piston rod combination to move rearward. The piston rod moves rearward and is connected to a bolt assembly for extraction of a cartridge, and the loading of another cartridge from the rifle&#39;s magazine. The bolt assembly must clear the magazine entirely before a new cartridge is placed in the chamber for firing. 
   For example, U.S. Pat. No. 5,123,329 discloses a trigger mechanism that when activated causes an inner movable barrel to move towards the breech block. A piston attached to the muzzle provides momentum to forwardly move the barrel past the cartridge feeding mechanism. When moving backwardly the inner barrel picks up a new cartridge to force against the firing pin of the breech block. U.S. Pat. Nos. 5,351,598 and 5,520,019 reveal the M16 gas piston assemblies variation wherein the piston moves rearward in relation to the bolt assembly. These semi-automatic rifles are based upon the piston moving rearward and activating the breechblock with a turning locking head. 
   It is an object of the present invention to provide a gas operated semi-automatic rifle having a gas piston under the discharge end of the barrel which ultimately moves the breechblock. Such a design allows the gas piston to be connected to a locking mechanism which in turn provides the rearward impetus for the breechblock in reloading a cartridge from the rifle magazine. 
   It is a further object of the invention to provide a breechblock which moves fore and aft, without a turning head, to load a new cartridge after discharge. 
   It is a feature of the invention that the gas piston, locking mechanism and breechblock combination move in synchrony using fewer moving parts and providing greater stability in operation of the rifle. 
   It is an advantage of the present invention that a gas operated semi-automatic rifle is provided which is lightweight and shorter in length, thus leading to ease of use and greater accuracy. 
   SUMMARY OF THE INVENTION 
   The general purpose of the present invention, which will be described subsequently in greater detail, is to provide a new and improved semi-automatic rifle with less movement of heavier parts. 
   To attain this, the present invention comprises, in combination, a rifle with a gas piston located under its barrel. During operation, when the piston receives the expanding gases from a fired cartridge, the piston moves a short distance forward. The gas piston is connected to a locking mechanism via a piston rod. The piston rod is not connected to a breechblock, as is present in many current models of gas operated semi-automatic rifles. When the gas piston and the piston rod move forward, the gas piston and piston rod disengage the locking mechanism from the breechblock. 
   The breechblock is located at the entry end of the rifle barrel. The barrel is positioned in a lower corps, and the breechblock is engaged to the barrel by the locking mechanism. When the locking mechanism disengages from the breechblock, the breechblock moves rearward and loads a new cartridge from a rifle magazine. The magazine is located rearward of the breechblock and trigger mechanism. 
   Most semi-automatic rifles currently in service are based on gas-propelled piston moving rearward and activating a breechblock with a turning locking head. This requires a number of heavy parts moving together. An advantage of the present invention is that the gas piston only moves a short distance forward and the breechblock moves rearward when loading a cartridge without turning in relation to its longitudinal axis. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein: 
       FIG. 1   a  is a cross sectional side view of the rear area of the present invention. 
       FIG. 1   b  is a cross sectional side view of the front area of the present invention. 
       FIG. 2  is an exploded side view of some components of the present invention. 
       FIGS. 3   a ,  3   b ,  3   c  and  3   d  are, respectively, a side view, top view, rear view and front view of the breechblock of the present invention. 
       FIGS. 4   a ,  4   b  and  4   c  are, respectively, a side view, front view and top view of the locking mechanism of the present invention. 
       FIGS. 5   a  and  5   b  are, respectively, a side view and top view of the initial loading mechanism of the present invention. 
       FIG. 6  is a cross sectional view of the gas piston and chamber of  FIG. 1   b  taken at line  6 - 6  of  FIG. 1   b.    
       FIG. 7  is a cross sectional view of the gas piston and chamber of  FIG. 1   b  taken at line  7 - 7  of  FIG. 1   b.    
       FIG. 8  is a cross sectional view of the breechblock of  FIG. 3   b  taken at line  8 - 8  of  FIG. 3   b.    
       FIG. 9  is a cross sectional top view of the present invention of the breechblock, the locking mechanism and the loading mechanism, when the barrel is removed. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 2  illustrates the main housing components of the invention  10  having an upper corps  12  and a lower corps  11 . The relative positioning of a barrel  17 , a breechblock  15  and a barrel compensator  24  are also illustrated in  FIG. 2 . 
   Now with reference to  FIGS. 1   a ,  1   b  and  2 , the lower corps  11  has a bottom surface, side walls and a front and rear section, along with a top perimeter channel  55 . A cavity is defined by the side walls. A locking mechanism  36 , a gas piston  28  and piston rod  30  are contained within the cavity of the lower corps  11 . Near the rear section of the lower corps  11 , a magazine  39  with rifle cartridges is located and is secured to the lower corps  11  via a magazine ketch  38 . The barrel  17  is securely mounted within the inner channel of the lower corps  11 . Preferably the channel is lined with sheet metal to increase the strength of connection with the barrel  17 . The lining of the channel is further constructed as channels to direct the movement of the breechblock  15 . The top perimeter edge  55  allows the lower corps  11  to mate with the upper corps  12 . Space for the magazine  39  is also provided, and the lower corps  11  has lining comprised of sheet metal  60  to increase its strength and to receive the barrel  17 . 
   The upper corps  12  has a top surface, side walls and a front and rear section, along with a bottom perimeter ridge  56 . The bottom perimeter ridge  56  slides into the top perimeter channel  55  of the lower corps  11  to mate the upper corps  12  with the lower corps  11 . As illustrated in  FIG. 6 , a chamber  21  is integrally formed in the upper corps  12  for the gas piston  28  near the front end of the upper corps  12 . Longitudinal channels  59  can be provided on the walls of the gas piston chamber  21 . When in the back position the piston  28  covers the channels  59 . After its movement forward, the piston  28  passes in front of the channels  59  and relieves excessive amount of gases. The upper corps  12  contains a vibration-absorbing pad  19 , which after assembly stays on top of the barrel  17  and presses the barrel  17  down. At the distal end of the upper corps  12  a metal ring  22  is contained, and the ring  22  surrounds the front end of the barrel  17  and makes contact with the barrel compensator  24 . The ring  22  also contains a small fixing pin  25 , which keeps the compensator  24  in position after the compensator  24  is tightened. 
   The barrel  17 , having a rifled bore  18  extending forwardly along a longitudinal axis toward a discharge end, a cartridge chamber  16 , and having a breech  58  integrally formed with the bore  18 . The barrel  17  has hills  31  to provide stability in the lower corps  11  and a generally circular shaped ketch  57  (illustrated in  FIG. 2 ) where an eccentric pin from the lower corps  11  fixes its position. The lower surface of the breech  58  is shaped sloping to direct the cartridge, when pushed by the breechblock  15 . At its discharge end the barrel  17  is outwardly threaded to mate with the compensator  24 . 
   In typical operation, the rifle as illustrated in  FIGS. 1   a  and  1   b  has a live round loaded in a cartridge chamber  16 . The rifle is fired utilizing a trigger  33 , grip  34 , and a trigger rod  35  connected to a hammer  37 . The cartridge is ignited by a firing pin  13 . The gas piston  28  and the piston rod  30  are mounted in the lower corps  11 , with the gas piston  28  being located under the barrel  17 . The gas piston  28  and piston rod  30  are flexibly connected to the locking mechanism  36 , and form a lever system. Gases are produced by the explosion of a rifle cartridge and movement of the round down the barrel  17 . The expanding gases from the cartridge explosion enter an opening  20  in the barrel wall approximately 100 mm before its discharge end, and enter an expansion chamber  29  formed rearward of the gas piston  28 . The expanding gases move the gas piston  28  approximately 15 mm forward. The piston rod  30  pulls the locking mechanism  36  and rotates the locking mechanism  36  along its axis. The rotational movement pulls down the locking mechanism  36 , and the breechblock  15  is released. 
   As illustrated in  FIG. 6 , the gas piston  28  is generally square in cross-section, and its top surface is juxtaposed to slide along the bottom surface of the barrel  17  when in operation. The gas piston  28  is surrounded on three of its sides by the upper corps  12 . 
   As further illustrated in  FIGS. 6 and 7 , the distal end of the gas piston  28  is integrally formed as a bar  26 , with a spring  27  surrounding the bar  26 . The bar  26  is mounted within the lower corps  11 , and the spring  27  fixes the movement of the gas piston  28 , reduces its speed and returns the gas piston  28  to its back position. The expanding gases from the cartridge explosion entering the expansion chamber  29  delay the movement of the gas piston  28  so that the breechblock  15  opens at the first end of the barrel  17  only after the pressure in the bore  18  is reduced. 
   A detailed illustration of the locking mechanism  36  is shown in  FIGS. 4   a ,  4   b  and  4   c . The locking mechanism  36  is mounted in the lower corps  11  of the rifle. Two locking fingers  42  and an operating lever  40  are integrally formed as part of the locking mechanism  36 . An arm  41 , mounted in cylinders  43  (illustrated in  FIG. 1   a ) built into the side walls of the lower corps  11 , allows the locking mechanism  36  to rotate along its axis. As shown in  FIG. 1   a , a spring  44  keeps the locking mechanism  36  in an upper position. The right locking finger  42  has an appendage  45  with a sloping surface which contacts with a loading handle  48  for initial loading. The piston rod  30  passes between the locking fingers  42  and through the operating lever  40  of the locking mechanism  36 . 
   The loading mechanism  64  is located in the right wall of the lower corps  11 , and illustrated in  FIGS. 5   a ,  5   b  and  9 . It is comprised of a rod  46  with a spring  47  and the loading handle  48 . When pulled back manually by a user of the rifle the handle  48  makes contact with the appendage  45  of the right locking finger  42  of the locking mechanism  36 , and pushes the right locking finger  42  downwardly. The breechblock  15  is released and is pushed back manually with the handle  48 . Moving rearward the breechblock  15  engages and rotates the hammer  37 , which is then set in a cocked position. At the final rearward the spring  47  is compressed. When the loading handle  48  is released the spring  47  returns to its former position. The breechblock  15  is now disengaged, and recoil springs  50  bias the breechblock  15  forward. The breechblock  15  strips a new top cartridge from the magazine  39  and positions the new cartridge within the cartridge chamber  16  formed in the barrel  17 , loading the rifle. The loading mechanism  64  remains immovable during firing. 
   Details of the breechblock  15  are illustrated in  FIGS. 3   a - d  and  FIG. 8 . The breechblock  15  has a first and second end, and surrounds the entry end of the barrel  17 . The breechblock  15  is coupled with the hammer  37 . When in the front position the breechblock  15  is juxtaposed behind the barrel  17 . At its final rearward position, after striping a cartridge from the magazine  39 , the breechblock  15  will pass approximately only 20 mm behind the magazine  39 . The total length of the rifle is thus reduced. 
   Recoil rods  49 , having first and second ends, extend from the first end of the breechblock  15 . Recoil springs  50  are positioned on the recoil rods  49 . The recoil rods  49  are engaged to fixing rings  51  at the second end of the recoil rods  49 . The second end of the recoil rods  49  and the fixing rings  51  are shaped conically which allows the rods  49  and the fixing rings  51  to engage. The sliding rings  52 , having an opening with a diameter greater than the diameter of the recoil rods  49 , are mounted in an immobile position in the lower corps  11 . The recoil rods  49  are extended through the opening of the sliding rings  52 . The breechblock  15 , when disengaged from the locking mechanism  36 , can move rearward along a longitudinal axis. The breechblock  15 , recoil rods  49  and fixing rings  51  move as an integral unit longitudinally. The recoil springs  50  bias the movement of the breechblock  15  during reloading. The breechblock  15 , and gas piston  28  and piston rod  30 , move fore and aft, and in opposite directions. 
   As illustrated in  FIG. 8 , the breechblock  15  has a firing pin  13 . An extractor  53 , extractor spring  62 , an ejector  54  and ejector spring  61 , act in combination to remove spent cartridges. A breechblock plug  63  is mounted in position in the breechblock  15 , and the extractor  53  and the ejector  54  are positioned therein. The breechblock plug  63  keeps the extractor  53  and ejector  54  in position and limits the movement of the firing pin  13 . A fixing pin  14  (shown in  FIG. 1A ) keeps the breechblock plug  63  in position. The extractor  53  and the ejector  54  are interchangeable for use by left or right handed shooters by changing the positions of the extractor  53  and the ejector  54 , and by rotating the breechblock plug  63 . 
   The extractor  53  has a first end and a second end, with a hooked shaped portion depending from the first end of the extractor  53 . After firing of a round, and as the breechblock  15  moves rearward, the hooked shaped portion of the extractor  53  removes the spent cartridge from the cartridge chamber  16 . The ejector  54  propels the spent cartridge form the rifle  10 , and allows the breechblock to reload another round. 
   The barrel compensator  24 , in addition to reducing recoil, completes the rifle assembly. The barrel compensator  24  is inwardly treaded to mate with the discharge end of the barrel  17 . When in its fixed position, the compensator  24  moves the barrel  17  forward. Since the barrel  17  is already fixed in the lower corps  11  the tightening of the compensator  24  pushes the upper corps  12  rearward. As a result the front end of the barrel  17  is secured against vibrations. The fixing pin  25  of the upper corps  12  keeps the compensator  24  on final position. A chamber  23  is integrally formed at the beginning of the compensator  24  to collect burning gases from the projectile explosion. 
   To assemble the rifle, first insert the rear end of the barrel  17  into the breechblock  15  and place both the barrel  17  and breechblock  15  into the lower corps  11 . The position of the barrel  17  is fixed with an eccentric pin  32 . Rear rings  52  of the recoil springs  50  are secured. The upper corps  12  is slide fully rearward, and the barrel compensator  24  is mounted to the barrel  17  to bias the upper corps  12  rearward. The barrel compensator  24  is fixed into position with the pin  25 . 
   With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function, and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. 
   Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, if is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.