Patent Publication Number: US-9404695-B2

Title: Gas systems for firearms

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to, incorporates herein by reference, and is a non-provisional of co-pending U.S. Patent Application No. 61/917,242, filed Dec. 17, 2013. 
    
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     None. 
     TECHNICAL FIELD 
     This invention relates to firearms, and in particular to improved gas systems for firearms. 
     BACKGROUND 
     Gas-operation is a system used to provide energy to operate auto-loading firearms. In gas-operation, a portion of high pressure gas from the cartridge being fired is used to power a mechanism to extract the spent case and chamber a new cartridge. Energy from the gas is harnessed through either a port in the barrel or trap at the muzzle. This high-pressure gas impinges on a movable surface such as a piston head to provide motion for unlocking the action, extracting and ejecting the spent case, cocking the hammer or striker, chambering a fresh cartridge, and locking the action. 
     Most current gas systems employ some type of piston. The face of the piston is acted upon by gas from the combustion of the propellant from the barrel of the firearm. Early methods such as Browning&#39;s ‘flapper’ prototype, the Bang rifle, and Garand rifle used relatively low-pressure gas from at or near the muzzle, where the bullet exits the barrel. This, combined with more massive operating parts, reduced the strain on the mechanism. To simplify and lighten the firearm, gas from nearer the chamber needed to be used. This gas is of extremely high pressure and has sufficient force to destroy a firearm unless it is regulated somehow. Several methods are employed to regulate the energy. The M1 carbine incorporates a very short piston, or “tappet”. This movement is closely restricted by a shoulder recess. Excess gas is then vented back into the bore. The M14 rifle and 60 GPMG use the White expansion and cutoff system to stop (cut off) gas from entering the cylinder once the piston has traveled a short distance. Most systems, however, vent excess gas into the atmosphere through slots, holes, or ports. 
     With a long-stroke system, the piston is mechanically fixed to the bolt group and moves through the entire operating cycle. This system is used in weapons such as the Bren light machine gun, AK-47, Tavor, M249 Squad Automatic Weapon, FN MAG, M1 Garand, and various semi-automatic shotguns, for example. The primary advantage of the long-stroke system, beyond design simplicity and robustness, is that the mass of the piston rod adds to the momentum of the bolt carrier enabling more positive extraction, ejection, chambering, and locking. Also, as the gas is not directed back into the chamber, the weapon stays cleaner longer thus reducing the likelihood of a malfunction. 
     Simplified section views of a typical gas-operation system in use are depicted in  FIGS. 1A-1E . A typical long-stroke gas-operation system  100  of a firearm may comprise a barrel  105  having a gas port  110  located distally down the barrel  105 , well away from the chamber  170 . The gas port  110  vents part of the pressurized gas  165  resulting from the firing of gunpowder  155  causing a bullet or other projectile(s)  150  (herein collectively, “bullet  150 ”) to travel down the barrel  105  from a proximal end near the chamber  170  to a distal end where the bullet exits the barrel  105  through a muzzle (not shown). The gas port  110  typically vents a small portion of the pressurized gas  165  into an adjacent cylinder  115  just beyond a piston  120  located in the cylinder  115 , as depicted in  FIGS. 1B-1D . The piston  120  is typically connected by a piston rod or operation rod  125  to a bolt carrier  130 , those parts together comprising a carrier assembly that typically slides in the opposite direction of the bullet  150  (i.e., rearward, or to the right in the Figures) when the pressurized gas  165  travels down the barrel  105  behind the bullet  150 , through the gas port  110 , into the cylinder  115 , and impinges on the face of the piston  120 , as depicted in  FIGS. 1B-1D . The momentum of the rearward travel of the bolt carrier assembly typically causes the bolt carrier  130  to unlock a locking block  145  that locks the bolt  140  to the chamber  170  (i.e., unlocks the “action”), and then the bolt carrier  130  pushes the bolt  140  backwards (to the right in the Figures) away from the chamber  170 , while expelling the spent casing  160  and introducing a new cartridge with bullet  150  into the chamber  170 , as depicted in  FIG. 1E . The rearward travel of the carrier assembly is typically increasingly resisted by a spring  135 , which then urges the carrier assembly to travel back in the forward direction (to the left in the Figures, FIG. IF), re-locking the bolt  140  to the chamber  170 , whereupon the firearm returns to the position shown in  FIG. 1A , ready to fire again. 
     One disadvantage of this type of system  100  is that, due to the significant mass of moving parts, a significant amount of high-pressure gas  165  is required to operate the system  100 . In order to transmit the required volume of high-pressure gas  165  to the piston  120 , manufacturers utilize various numbers of gas ports  110  of different sizes, typically located near or distally (to the left in the Figures) of the resting position of the piston  120  to allow the high-pressure gas  165  to flow backward (to the right in the Figures) against the face of the piston  120 . There are some key limitations to this type of system  100 . First, these small ports  110  are prone to clogging due to debris created when a round or bullet  150  is fired. Clogged ports  110  can cause the firearm to cease functioning as intended. 
     Second, the size and/or number of ports  110  can directly affect the types of loads that can be used. If the ports  110  are small or there are few of them it is more difficult for high-pressure gas  165  to be redirected to the piston  120 . This results in the firearm requiring heavy loads (high-powered cartridges) in order for the gas-operation system  100  of the firearm to cycle. Alternatively, if ports  110  are larger or more numerous then gas  165  is more easily redirected, which can allow the firearm to cycle lighter loads (lower-powered cartridges). However, where large ports  110  are used, heavy loads may cause excessive wear on the firearm due to exposing the face of the piston  120  to an excessive volume of high-pressure gas  165  directly from the interior of the barrel  105 . 
     A third limitation of typical systems  100  is the distal location of the ports  110 . By placing the ports  110  in a distal portion of the barrel  150  (distally from the firing chamber  170 ) adjacent or beyond the resting position of the piston  120 , the pressure of the high pressure gas  165  available at the ports  110  is greatly reduced and is widely variable depending on the power of the cartridge  150 . Thus, present systems  100  provide inefficient and inconsistent capturing and transmission of high-pressure gas  165 . 
     SUMMARY 
     Provided is a novel structure, system, and method for gas-operating firearms that elegantly overcomes the problems of the prior art while providing other advantages. Provided in various example embodiments is a gas system for a firearm having a barrel, comprising: one or more gas ports in gaseous communication with high-pressure gas in the interior of a firearm through an annular gas ring, the one or more gas ports in gaseous communication with a piston adapted to cycle the firearm using the high-pressure gas communicated through the one or more gas ports; wherein the annular gas ring comprises a longitudinally-extending segment through which a projectile fired by the firearm travels, the annular gas ring having a diameter larger than an inner diameter of the barrel. In various example embodiments the gas system may further comprise the annular gas ring positioned proximate a chamber adapted to house a cartridge to be fired by the firearm. In various example embodiments the gas system may further comprise the piston being located distally from the annular gas ring and the one or more gas ports being in gaseous communication with the piston through one or more longitudinally-extending gas tubes. In various example embodiments the gas system may further comprise the annular gas ring being formed in the inner diameter of the barrel. In various example embodiments the gas system may further comprise the annular gas ring being formed in the inner diameter of a chamber housing adapted to house a cartridge to be fired by the firearm. In various example embodiments the gas system may further comprise the annular gas ring being formed between a proximate end of the barrel and a distal end of a chamber housing adapted to house a cartridge to be fired by the firearm. In various example embodiments the gas system may further comprise a coupler comprising a longitudinally-extending inner circumferential surface open on two ends, a first end of the coupler adapted to receive therein the proximate end of the barrel, and a second end of the coupler adapted to receive therein the distal end of the chamber housing, such that the proximate end of the barrel and the distal end of the chamber housing are located proximate but separated from each other by a predetermined longitudinal distance within the coupler. In various example embodiments the gas system may further comprise the one or more ports being formed in the coupler. In various example embodiments the gas system may further comprise the piston being located distally from the annular gas ring and the one or more gas ports being in gaseous communication with the piston through one or more longitudinally-extending gas tubes. In various example embodiments the gas system may further comprise the one or more longitudinally-extending gas tubes comprising hollow cylinders separable from the rest of the firearm. In various example embodiments the gas system may further comprise the one or more gas ports in gaseous communication with the piston through a gas block, the gas block adapted to be in gaseous communication with the one or more longitudinally-extending gas tubes and with a cylinder housing the piston. In various example embodiments the gas system may further comprise the gas block further adapted to surround and support the barrel. In various example embodiments the gas system may further comprise the gas block and the cylinder housing the piston being one piece. 
     Provided in another example embodiments is a modular gas system for a firearm having a barrel, comprising: one or more gas ports in gaseous communication with high-pressure gas in the interior of a firearm, the one or more gas ports in gaseous communication with a piston adapted to cycle the firearm using the high-pressure gas communicated through the one or more gas ports; the one or more gas ports positioned proximate a chamber adapted to house a cartridge to be fired by the firearm; the piston located distally from the one or more gas ports; and the one or more gas ports in gaseous communication with the piston through one or more longitudinally-extending gas tubes. In various example embodiments the modular gas system may further comprise a coupler comprising a longitudinally-extending inner circumferential surface open on two ends, a first end of the coupler adapted to receive therein a proximate end of the barrel, and a second end of the coupler adapted to receive therein a distal end of a chamber housing, the chamber housing comprising therein a chamber adapted to house a cartridge to be fired by the firearm, the proximate end of the barrel and the distal end of the chamber housing located proximate but separated from each other by a predetermined longitudinal distance within the coupler. In various example embodiments the modular gas system may further comprise the one or more ports being formed in the coupler. In various example embodiments the modular gas system may further comprise the one or more longitudinally-extending gas tubes comprising hollow cylinders separable from the rest of the firearm. In various example embodiments the modular gas system may further comprise the one or more gas ports in gaseous communication with the piston through a gas block, the gas block adapted to be in gaseous communication with the one or more longitudinally-extending gas tubes and with a cylinder housing the piston. In various example embodiments the modular gas system may further comprise the gas block being further adapted to surround and support the barrel. In various example embodiments the modular gas system may further comprise the gas block and the cylinder housing the piston being one piece. 
     The foregoing summary is illustrative only and is not meant to be exhaustive or limiting. Other aspects, objects, and advantages of various example embodiments will be apparent to those of skill in the art upon reviewing the accompanying drawings, disclosure, and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a side elevation section view of a simplified long-stroke gas-operation system of known firearms, shown loaded and ready to fire. 
         FIG. 1B  is a side elevation section view of the system of  FIG. 1A , shown immediately after firing, as a bullet leaves the firing chamber and begins to travel down the barrel. 
         FIG. 1C  is a side elevation section view of the system of  FIG. 1B , shown a short time later, as the bullet travels distally down the barrel. 
         FIG. 1D  is a side elevation section view of the system of  FIG. 1C , shown a short time later, as the bullet travels past a gas port, allowing high-pressure gas behind the bullet to travel through the gas port to impinge on a piston, thereby causing a carrier assembly to begin to move backward (i.e., to the right). 
         FIG. 1E  is a side elevation section view of the system of  FIG. 1D , shown a short time later, as the carrier assembly continues to move backward (to the right) via momentum, thereby actuating the action of the firearm to automatically reload the firearm. 
         FIG. 1F  is a side elevation section view of the system of  FIG. 1E , shown a short time later, as the carrier assembly returns toward its starting position as shown in  FIG. 1A . 
         FIG. 2A  is a side elevation section view of a simplified long-stroke gas-operation system of a firearm improved according to various example embodiments of the present disclosure, shown loaded and ready to fire. 
         FIG. 2B  is a side elevation section view of the system of  FIG. 2A , shown immediately after firing, as a bullet leaves the firing chamber and begins to travel down the barrel, as the bullet travels past a gas port formed in an internal annular ring, allowing high-pressure gas behind the bullet to travel through the gas port, through a gas tube, to impinge on a piston, thereby causing a carrier assembly to begin to move backward (i.e., to the right). 
         FIG. 2C  is a side elevation section view of the system of  FIG. 2B , shown a short time later, as the carrier assembly continues to move backward (to the right) and begins to engage the action of the firearm. 
         FIG. 2D  is a side elevation section view of the system of  FIG. 2C , shown a short time later, as the carrier assembly continues to move backward (to the right) via momentum, thereby actuating the action of the firearm to automatically reload the firearm. 
         FIG. 2E  is a side elevation section view of the system of  FIG. 2D , shown a short time later, as the carrier assembly returns toward its starting position as shown in  FIG. 2A . 
         FIG. 3  is a side elevation section view of a long-stroke gas-operation system of a firearm improved according to various example embodiments of the present disclosure. 
         FIG. 4  is an exploded perspective view of the example system of  FIG. 3 , showing various example components. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Reference will now be made in detail to some specific example embodiments, including any best mode contemplated by the inventor. Examples of these specific embodiments are illustrated in the accompanying drawings. While the invention is described in conjunction with these specific embodiments, it will be understood that it is not intended to limit the invention to the described or illustrated embodiments. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. 
     In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. Particular example embodiments may be implemented without some or all of these features or specific details. In other instances, components and procedures well known to persons of skill in the art have not been described in detail in order not to obscure inventive aspects. 
     Various techniques and mechanisms will sometimes be described in singular form for clarity. However, it should be noted that some embodiments may include multiple iterations of a technique or multiple components, mechanisms, and the like, unless noted otherwise. Similarly, various steps of the methods shown and described herein are not necessarily performed in the order indicated, or performed at all in certain embodiments. Accordingly, some implementations of the methods discussed herein may include more or fewer steps than those shown or described. 
     Further, the example techniques and mechanisms described herein will sometimes describe a connection, relationship or communication between two or more items or entities. It should be noted that a connection or relationship between entities does not necessarily mean a direct, unimpeded connection, as a variety of other entities or processes may reside or occur between any two entities. Consequently, an indicated connection does not necessarily mean a direct, unimpeded connection unless otherwise noted. 
     Referring now in detail to the drawings wherein like elements are indicated by like numerals, there are shown various aspects of example firearms with improved gas systems. With respect to the example embodiments shown in  FIGS. 2A-2E, 3 and 4 , in one aspect gas systems  200 ,  300  may be provided with gas ports  210 ,  310  that may be in gaseous communication with high-pressure gas  165  in the interior of a firearm through an annular gas ring  207 ,  307 . Annular gas ring  207 ,  307  may comprise a longitudinally-extending segment through which the projectile  150  travels, which has a diameter larger than the inner diameter of the barrel  205 ,  305 . An annular gas ring  207 ,  307  can be machined or otherwise formed into the inner diameter of the barrel  205 ,  305  or the chamber housing  371 , or may be defined by a member connecting the barrel  305  with the firing chamber  370 , such as a coupler  390  (shown in  FIGS. 3 and 4 ). Annular gas ring  207 ,  307  may have any suitable cross-sectional profile, such as curved, angled, or squared-off, and may be defined by a locus of points separated from the centerline of the barrel  205 ,  305  by a constant radial distance, or may have a variable radial distance, for instance increasing near the one or more gas ports  210 ,  310 . It has been found that locating gas ports  210 ,  310  in annular gas rings  207 ,  307  surprisingly improves the efficiency with which high-pressure gas  165  is captured and directed into the gas ports  210 ,  310 . 
     In another example aspect of improved gas systems  200 ,  300 , one or more gas ports  210 ,  310  may be positioned proximate the firearms&#39; respective chambers  170 ,  370 . In these example embodiments, high-pressure gas  165  may be communicated from the highest pressure region in the firearm, near the chamber  170 ,  370 , through one or more gas ports  210 ,  310 , into one or more gas tubes  215 ,  365  that communicate the high-pressure gas  165  from proximate the chamber  170 ,  370  area, distally to a distally located piston  120 ,  320 . This has been found to provide the surprising benefit of almost instantaneously communicating to piston  120 ,  320  high-pressure gas  165  having significantly improved consistency in pressure, regardless whether heavy or light loads are used, while providing sufficient energy to drive piston  120 ,  320  even when very light loads are used. 
     With continuing reference to the example embodiment of an improved gas system  200  shown  FIGS. 2A-2E , which illustrates multiple aspects, in use one or more gas ports  210  vent part of the pressurized gas  165  resulting from the firing of gunpowder  155  causing a bullet or other projectile(s)  150  (herein collectively, “bullet  150 ”) to travel down the barrel  205  from a proximal end near the chamber  170  to a distal end where the bullet exits the barrel  205  through a muzzle (not shown). A portion of the high-pressure gas  165  proximate the chamber  170  is efficiently captured and directed into the one or more gas ports  210  by annular gas ring  207 , which is shown formed in the interior of the barrel  205  and proximate the chamber  170  in this embodiment. The one or more gas ports  210  communicate high-pressure gas  165  distally through one or more gas tubes  215 , through one or more cylinder ports  220 , into the cylinder  115 , where the high-pressure gas  165  impinges on the face of the piston  120 , as depicted in  FIGS. 2B-2C , all before the bullet  150  travels distally to the resting location of the piston  120 . This is an improvement over prior devices  100  that only begin to communicate high-pressure gas  165  to the piston  120  after the bullet  150  travels further down the barrel, typically distally near or past the end of the piston  120 , compare  FIGS. 1A-1D . 
     In various example embodiments, the piston  120  may be connected by a piston rod or operation rod  125  to a bolt carrier  130 , those parts together comprising a carrier assembly that may slide in the opposite direction of the bullet  150  (i.e., rearward, or to the right in the Figures) when the pressurized gas  165  travels down the barrel  205  behind the bullet  150 , through the gas ports  210 , through the gas tubes  215 , through one or more cylinder ports  220  into the cylinder  115 , where it impinges on the face of the piston  120 , as depicted in  FIGS. 2B-2C . In various example embodiments the momentum of the rearward travel of the bolt carrier assembly may cause the bolt carrier  130  to unlock a locking block  145  that locks the bolt  140  to the chamber  170  (i.e., unlocks the “action”), followed by the bolt carrier  130  pushing the bolt  140  backwards (to the right in the Figures) away from the chamber  170 , while expelling the spent casing  160  and introducing a new cartridge with bullet  150  into the chamber  170 , as depicted in  FIG. 2D . The rearward travel of the carrier assembly may be increasingly resisted by a spring  135 , which may then urge the carrier assembly to travel back in the forward direction (to the left in the Figures,  FIG. 2E ), re-locking the bolt  140  to the chamber  170 , whereupon the firearm returns to the position shown in  FIG. 2A , ready to fire again. 
     Since the present system  200  can communicate pressure to the piston  120  more quickly than prior systems  100 , the present system  200  may be adapted to cycle more rapidly than prior devices  100  as shown in  FIGS. 1A-1D . Additionally, by tapping into the highest available pressure gas  165  near the chamber  170 , efficiently capturing and directing that highest-pressure gas with an annular gas ring  207 , and then communicating that highest-pressure gas  165  through distally-extending gas tubes  215  and cylinder ports  220 , the volume and pressure of gas  165  available at the piston  120  may be significantly improved in consistency, regardless whether heavy or light loads are used, while reliably providing sufficient energy to drive piston  120 ,  320  even when very light loads are used. 
     Certain details regarding another example embodiment are illustrated in  FIGS. 3 and 4 . Operating as set forth above with respect to example gas system  200 , an example gas system may comprise a modular system  300  comprising a barrel  305  having a proximate end  306 , a chamber housing  371  defining therein a chamber  370  and having a distal end  372 , a coupler  390  comprising a longitudinally-extending inner circumferential surface  391  open on two ends, one end of the coupler  390  adapted to receive therein the proximate end  306  of the barrel  305 , and the other end of the coupler  390  adapted to receive therein the distal end  372  of the chamber housing  371 , such that the proximate end  306  of the barrel  305  and the distal end  372  of the chamber housing  371  are located proximate but separated from each other by a predetermined longitudinal distance within the coupler  390 . When assembled as shown in  FIG. 3 , the space within the coupler  390  defined between the proximate end  306  of the barrel  305  and the distal end  372  of the chamber housing  371  is annular gas ring  307 , into which gas ports  310  are formed. Gas ports  310 , formed in coupler  390 , may be adapted to be in gaseous communication with respective longitudinally-extending cylindrical gas tubes  365  each having their own body, which may be adapted to be in further gaseous communication with gas block  395 , which may comprise corresponding cylinder ports  396  ( FIG. 3 ) in gaseous communication with the face of piston  320  within cylinder  315 . Gas block  395  may be adapted to surround and support the outer diameter of barrel  305  and may be formed as one-piece with the cylinder  315  ( FIG. 4 ). For ease of maintenance and manufacture a removable and replaceable gas plug  380  may be located in the distal end of cylinder  315  to access the interior of cylinder  315 . Piston  320  may be attached with operation rod / carrier assembly  325 , which may function in a firearm as described above with respect the corresponding parts illustrated in  FIGS. 2A-2E , or in any other suitable manner. In other embodiments, longitudinally-extending gas tubes  365  may not have their own body, and may be formed as part of another component, for instance as a through-hole or chamber formed in another component, for instance as shown in gas tube  215  in  FIG. 2A . 
     It is understood that the above-described embodiments are merely illustrative of the application. Other embodiments may be readily devised by those skilled in the art, which may embody one or more aspects or principles of the invention and fall within the scope of the claims.