Abstract:
A semi-automatic rifle is configured to fire single rounds of ammunition via a magazine or a belt of ammunition. A receiver cover pivots open to receive the first round of a belt of ammunition or a magazine can be inserted in a magazine well. The rifle operates using a closed bolt firing cycle, with a sliding hammer that, on its return from recoil after firing a first round, is caught by a sear regardless of whether the trigger is still in the pulled position. The trigger must be fully released before a second round can be fired.

Description:
TECHNOLOGICAL FIELD 
       [0001]    The present disclosure relates generally to firearms. More specifically, it relates to semi-automatic rifles. 
       BACKGROUND 
       [0002]    Firearms for hunting and sport shooting come in a range of types, such as traditional hunting rifles with wood butt stocks and fore stocks to military type rifles. In the latter group, there is an interest in rifles that have military ruggedness and appearance but meet requirements for ownership and use, such as, for example, a limitation to semi-automatic mode rather than fully-automatic operation. Semi-automatic mode means that the trigger must be released for the next round to be fired. If the trigger is pulled but not released, one round only is fired. 
       BRIEF SUMMARY 
       [0003]    The present disclosure is of a rifle having the features typical of light machine guns but operates only in semi-automatic mode. For example, it may be fed ammunition using an ammunition belt, its receiver has a pivoting cover to admit the first round of the belt, and it has charging handle similar to those of military machine guns. 
         [0004]    The present rifle has a barrel, a buttstock, a receiver, and a trigger. The barrel has a forward end and an opposing rearward end and may be covered on top and on the bottom by a heat shielding. A breech is formed in the rearward end of the barrel where it is joined to the forward end of the receiver. A buttstock is attached to the rearward end of the receiver. The trigger is held within a trigger housing attached to the underside of the receiver. The trigger housing may also include a pistol grip. 
         [0005]    A feature of the present rifle is that the receiver is configured to receive ammunition from a belt and, according to the preference of the user, from a magazine without modification. It has a magazine well to receive an ammunition magazine and a ramp for belt-fed ammunition with a receiver top cover that pivots open to allow the first round of a belt of ammunition to be put in position for loading into the breech. 
         [0006]    The present rifle includes a bolt, a firing pin carried by the bolt, a sliding hammer, and a spring system for urging the hammer to move forward in the receiver to strike the firing pin. The operation of the bolt seats the next round, extracts the spent cartridge casing after firing, and pulls into position the next round as part of the firing cycle. The trigger assembly includes a trigger, a disconnector that pivots a sear when said trigger is pulled. The sear automatically catches the hammer on recoil and holds it until the disconnector, lifted by the pull of the trigger, again pivots the sear to release the hammer. 
         [0007]    The charging handle is on the right side of the receiver with a forward and rearward position and is used to seat the first round in the breech. The present rifle has a broad heat shield extending over, and a hand guard under, the barrel, and a mid-position carrying handle that adds to the light-machine gun appearance of the present semi-automatic rifle. 
         [0008]    Another feature of the disclosure is that the firing pin is slidably carried within the bolt so that the pin travels with the bolt but also moves with respect to the bolt when the pin is struck by the sliding hammer. 
         [0009]    Another feature of the disclosure is the rails formed on the interior of the receiver housing. The hammer rides on the rails between the forward end of the receiver and the rearward end. 
         [0010]    A feature of the disclosure is a spring that urges the trigger to move against a second pin in the trigger housing, after the trigger returns to the released position, with an audible and tactile click so that the user hears and feels that the trigger has seated in the released position and that, therefore, the trigger is again ready to pull in order to fire another round of ammunition. 
         [0011]    These and other features and their advantages will be apparent to those skilled in the firearm arts from a careful reading of the detailed description of preferred embodiments accompanied by the following drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    In the drawings, 
           [0013]      FIG. 1  is a left side view of the semi-automatic rifle, according to an aspect of the disclosure. 
           [0014]      FIG. 2  is a top view of the semi-automatic rifle, according to an aspect of the disclosure. 
           [0015]      FIG. 3  is a right side view of the semi-automatic rifle, according to an aspect of the disclosure. 
           [0016]      FIG. 4  is a left side, partial cross-sectional, detailed view of the receiver of a semi-automatic rifle, according to an aspect of the disclosure. 
           [0017]      FIG. 5  is a right side, cross-sectional view of a trigger assembly of the semi-automatic rifle, according to an aspect of the disclosure. 
           [0018]      FIG. 6  is a left side, exploded view of the trigger assembly of the semi-automatic rifle, according to an aspect of the disclosure. 
           [0019]      FIG. 7  is a left side perspective view of the bolt of the semi-automatic rifle, according to an aspect of the disclosure. 
           [0020]      FIG. 8  is a top, cross-sectional view of the bolt of the semi-automatic rifle, according to an aspect of the disclosure. 
           [0021]      FIG. 9  is a left side, exterior view of the operating group showing the bolt and operating rod, according to an aspect of the disclosure. 
           [0022]      FIG. 10  is a left side, perspective view of the hammer of the semi-automatic rifle, according to an aspect of the disclosure. 
           [0023]      FIG. 11  is a right side view of the interior of the receiver of the semi-automatic rifle, according to an aspect of the disclosure. 
           [0024]      FIG. 12  is a left side view of the interior of the receiver and part of the barrel of the semi-automatic rifle with the bolt shown in cross-section revealing the hammer on the sear, according to an aspect of the disclosure. 
           [0025]      FIG. 13  is a left side view of the interior of the receiver and part of the barrel of the semi-automatic rifle with the bolt shown in cross-section revealing the hammer moving toward the firing pin, according to an aspect of the disclosure. 
           [0026]      FIG. 14  is a right side view of the interior of the receiver showing the position of the hammer at the moment it strikes the firing pin, according to an aspect of the disclosure. 
           [0027]      FIG. 15  is a left side view of the interior of the receiver showing the hammer at the moment it strikes the firing pin, according to an aspect of the disclosure. 
           [0028]      FIG. 16  is a right side view of the interior of the receiver with the hammer and bolt in the process of recoiling after firing a round, according to an aspect of the disclosure. 
           [0029]      FIG. 17  is a left side view of the interior of the receiver with the hammer and bolt partially recoiled after firing a round, according to an aspect of the disclosure. 
           [0030]      FIG. 18  is a right side view of the interior of the receiver showing the bolt and hammer fully recoiled, according to an aspect of the disclosure. 
           [0031]      FIG. 19  is a left side view of the interior of the receiver showing the bolt and hammer fully recoiled, according to an aspect of the disclosure. 
           [0032]      FIG. 20  is a left side view of the interior of the receiver showing the bolt and hammer returning after recoil and with the hammer now caught by the sear, according to an aspect of the disclosure. 
           [0033]      FIG. 21  is a right side view of the interior of the receiver showing the bolt closing into the barrel and the hammer held by the sear and poised to move forward once the trigger is pulled, according to an aspect of the disclosure. 
           [0034]      FIG. 22  is an end cross sectional view of the receiver, according to an aspect of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    In this disclosure, regarding a rifle, the terms proximal and rearward refer to the “butt stock” end of the rifle and forward or distal refer to the “barrel end” of the rifle, generally consistent with the perspective of a user who is holding the rifle in firing position. Similarly, upward and downward are from the perspective of a user standing and holding the firearm in normal orientation, that is, with the trigger oriented to extend toward the earth. The terms left side and right side are from the perspective of someone aiming the rifle. When introducing elements of the present disclosure or exemplary aspects or embodiment(s) thereof, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Although this disclosure has been described with respect to specific embodiments, the details of these embodiments are not to be construed as limitations. 
         [0036]    As seen in  FIGS. 1-3 , the present rifle  10  has a barrel  12 , a receiver  14 , a heat shield  16 , and a hand guard  18 . It also has a carrying handle  20 , a charging handle  22 , and a cover plate  24 . Below receiver  14  is a trigger assembly  26 . Attached to barrel  12  is a bipod  28 . On the proximal end of rifle  10  is a buttstock  30 . 
         [0037]    Rifle  10  is similar in appearance to a military firearm and a light machine gun in particular, because of features such as cover plate  24 , the side-mounted charging handle  22 , a dovetail ramp  32  for accepting a drum of ammunition ( FIG. 1 ), and the barrel heat shield  16  and hand guard  18 . Rifle  10  may receive single rounds of ammunition via a magazine or belt-fed ammunition. 
         [0038]    Although the appearance and many of the features of the present rifle  10  are similar to an M249 machine gun, for example, its firing mechanism is semi-automatic rather than fully automatic, that is, pulling and holding the trigger  34  causes only a single round of ammunition to be fired rather than a continuous series of rounds. Trigger  34  must be released for a second round to be fired. See US publication 2012/0144992 published by Landies, et al, which is incorporated herein in its entirety by reference, for a description of the operation of a conventional M249 machine gun. 
         [0039]      FIG. 4  illustrates a left side view of receiver  14  with part of receiver housing  40  cut away to show some of the individual components of receiver  14 . A round  42  of ammunition is shown seated in the barrel chamber  44 , which is formed in the proximal end of barrel  12  and held in place by the breech face of bolt  48 . A firing pin  46  is poised to fire round  42  as its distal tip is just proximal to the primer carried in the proximal end of the shell casing of round  42 . 
         [0040]    Firing pin  46  is carried inside a bolt  48 , shown in cross-section in  FIG. 4 . Bolt  48  is carried in a bolt carrier  52 , which has a slot  138  (seen in  FIG. 22 ), formed therein which receives a portion  130  of a sliding hammer  50 , also shown in cross-section in  FIG. 4  and in perspective in  FIG. 10 , which portion  130  is held in position to strike the proximal end of firing pin  46 . Sliding hammer  50  has pairs of corresponding grooves  124 ,  126 , on either side that ride on rails  152 ,  154  (seen in  FIG. 22 ). 
         [0041]    The movement of bolt  48  and sliding hammer  50  is controlled in part by two springs, an operating group spring  60  and a firing spring  62 . Operating group spring  60  and firing spring  62  are co-axial about an operating rod  56 , which are all seen, at least in part, in  FIG. 4  (and also in  FIG. 12 , for example). Firing spring  62 , shown in cross-section, has a larger diameter than operating group spring  60  and slows sliding hammer  50  by compressing during the rearward travel of hammer  50  on recoil and then provides the power to drive hammer  50  forward toward bolt  48  and firing pin  46  after being released by sear  70 . Spring  60  also compresses when operating group  58  is driven rearward by the diverted gas acting on the piston  114 , travels rearward and strikes the hydraulic buffer contained in the butt stock assembly and then extends when operating group  59  moves forward to return bolt  48  to its closed position. During its return from recoil, bolt  48  will strip a round  42  from a magazine or belt of ammunition and seat it in the barrel chamber  44 . 
         [0042]      FIGS. 5 and 6  show a right side view and a left side exploded view of trigger assembly  26 . Trigger assembly  26  includes a pistol grip  64  and a trigger guard  66 . Trigger  34  is pulled rearward (to the left in  FIG. 5 ) from its normal released position to a pulled position to fire round  42 . When pulled from its released position, trigger  34  lifts a disconnector  68  which pivots the distal end of sear  70  upward. The proximal end of sear  70  then pivots downward about pivot pin  72  which releases sliding hammer  50  from its hammer-catch position to its hammer-release position, as will be described more fully below. A trigger spring  74  resists rearward movement of trigger  34  and urges it forward to its release position. A trigger spring  74  urges sear  70  to return to its hammer-catch position after disconnector  68  pushes it upwardly to its hammer-release position. Accordingly, trigger  34  is spring-biased to its trigger-release position; sear  70  is spring-biased toward its hammer-catch position. 
         [0043]    Upper limit pin  78  limits the upper range of movement of proximal end of sear  70  which is reached when trigger  34  returns to the trigger-release position or disconnector  68  disconnects from sear, which produces an audible and tactile click to alert the user that a round  42  will be fired by the next pull of trigger  34 . Trigger spring  74  seats on trigger spring pin  82 . A safety  84  controls movement of trigger  34  by its axial position, which axial position either blocks or permits movement of trigger  34 . Pistol grip  64  is fastened to trigger assembly  26  by a threaded bolt  86 . 
         [0044]      FIGS. 7 and 8  show bolt  48  in perspective from the right front and in cross-section from the left side, respectively. Bolt  48  holds firing pin  46  which travels with bolt  48  from a distal position locked into barrel  12  to a proximal position toward butt stock  30 . Firing pin  46  also moves through only a limited additional range within, and respect to, bolt  48  when sliding hammer  50  strikes it. When sliding hammer  50  strikes firing pin  46 , firing pin  46  moves forward (to the right in  FIG. 7 , to the left in  FIG. 8 ). Firing pin  46  is shown in its forward-most position in  FIG. 8 . Forward movement of firing pin  46  loads a compression spring  100  that is relieved soon after the impact of sliding hammer  50  as it urges pin  46  rearward. 
         [0045]    Bolt  48  also performs the function of extracting a spent cartridge from barrel chamber  44  using an extractor  102 . Extractor  102  pivots around an extractor pivot pin  106  against the rim of the cartridge, which extractor  102  is biased by an extractor spring  104  against the cartridge rim. Finally, lugs  110  on the distal end of bolt  48  strip a new round  42  from a magazine or ammunition belt and seat it in barrel chamber  44 . 
         [0046]    Bolt  48  also pivots about its own axis as it moves axially. Bolt  48  rides in a bolt carrier  52 , seen in  FIG. 9 . A cam follower  108  on bolt  48  extends through a cam race  98  in cam housing  52  that causes bolt  48  to rotate in one direction through part of an arc as bolt travels in one axial direction and then through the same arc in the reverse direction when bolt  48  reverses its axial movement. Bolt carrier  52  travels forward and rearward on rails  118 ,  120  (best seen in  FIG. 22 ). 
         [0047]      FIG. 9  shows operating group  58  with an operating rod  56  carrying a piston  114  threaded to its distal end and a fitting  116  on its proximal end for attachment to bolt carrier  52 . As operating rod  56  moves forward and rearward, bolt carrier  52  and bolt  48  travel with it, moving rearward on recoil from the closed bolt position, in which bolt  48  is radially unlocked from barrel  12 , and then forward to the closed bolt position again in the next firing cycle. Piston  114  fits into the gas cylinder of rifle that receives a portion of the combustion gas from the firing of round  42  through a hole in barrel  12  which gas drives piston  114  and the balance of operating group  58  rearward. 
         [0048]      FIG. 10  shows sliding hammer  50  with the firing pin-engaging portion  130  extending upward from sliding hammer  50  where it will be received in a slot  138  in bolt carrier  52  (seen best in  FIGS. 4 and 22 ). Sliding hammer  50  has an axial hole  132  formed in it for receiving firing spring  60 , recoil spring  62  and operating pin  134 . 
         [0049]      FIGS. 11-21  illustrate relative movements of the present rifle  10  during sequential parts of the firing cycle.  FIGS. 11, 14, 16, 18, and 21  show the right side of receiver  14  with housing  40  removed.  FIGS. 12, 13, 15, 17, 19, and 20  show the left side of receiver  14 . 
         [0050]    In  FIG. 11  shows sliding hammer  50  held by sear  70  urged forward by firing spring  62  with bolt  48  forward in receiver  14  in its closed position radially locked in barrel  12 . Firing spring  62  is compressed, ready to propel sliding hammer  50  forward. Trigger  34  is in its released position. In  FIG. 12 , trigger  34 , in its released position, and sear  70  in its hammer catch position so sliding hammer  50  is held in place. 
         [0051]    In  FIG. 13 , trigger  34  is in its pulled position, which lifts disconnector  68  that in turn pivots sear  70  so its proximal end rotates up and its distal end rotates down, thereby releasing hammer  50 . 
         [0052]    In  FIGS. 14 and 15 , sliding hammer  50  has moved forward far enough so that its engaging portion  130  (see  FIGS. 10 and 15 ) has entered slot  138  in proximal end of bolt carrier  48  (see  FIGS. 15 and 22 ) and is poised to strike firing pin  46  ( FIG. 15 ). Note that sear  70  has already been reset by the biasing force of sear spring  76 . 
         [0053]      FIGS. 16 and 17  show sliding hammer  50 , now moving rearward toward buffer in butt stock  30  following the firing of round  42  of ammunition. The proximal end of sear  70  is cammed downward by the movement of sliding hammer  50  as it travels rearward but sear  70  immediately resets to its hammer-catch position to catch sliding hammer  50  when it moves forward again. Op group  58  moves rearward with sliding hammer  50 . 
         [0054]      FIGS. 18 and 19  show sliding hammer  50  having reached buffer  136  carried on the distal end of butt stock  30  and which stops rearward movement of sliding hammer  50 . Op group  58  also reaches its rearward-most position with sliding hammer  50 . Sear  70  is set to catch sliding hammer  50  as it rebounds off buffer  136 . 
         [0055]      FIGS. 20 and 21  show sliding hammer  50 , urged by firing spring  62 , moving forward to the point where it is caught by sear  70 , its forward movement halted. Op group  58 , however, continues its forward motion, separating from sliding hammer  50 . Bolt  48  again radially closes on barrel  12  as shown in  FIGS. 11 and 12  for the firing cycle to begin again. 
         [0056]      FIG. 22  shows a perspective, cross-sectional view of rifle  10 . Carrying handle  20  is shown in top right, above charging handle  22 . A magazine well  150  is shown on the left. Firing pin  46  is partially obscured by bolt carrier  52  but visible in through slot  138  in bolt carrier  52 . The rear part of the op rod  116  appears below bolt carrier  52  and operating group spring  60  and firing spring  62  are show in it with firing spring  62  being the spring of larger diameter. The top of sear  70  is shown below rear part  116 . Operating group spring  60  and firing spring  62  are also visible through hole  132  of sliding hammer  50 . Sear  70  is shown below hammer  50 . 
         [0057]    Rails  118 ,  120  on which bolt carrier  52  rides are seen to its left and right, respectively. Additional rails  152 ,  154 , which are received in grooves  124 ,  126  of sliding hammer  50  are shown below that on either side of sear  70 . 
         [0058]    Those skilled in firearms will appreciate from the foregoing description of aspects of the disclosure that many substitutions and modifications may be made without departing from the spirit and scope of the disclosed rifle, which is defined by the appended claims.