Abstract:
A firearm buffer system that reduces the rate of fire of a full automatic firearm that has a gas port wear and reduces the adverse effect of bolt bounce. The firearm buffer system includes a buffer assembly that has an elongated buffer body having an elongated hollow interior with a dosed end and an open end and a plurality of weights sized and shaped to reciprocate in the elongated hollow interior of the buffer body. Springs are located in the elongated hollow interior of the buffer body for positioning at least some of the weights apart from each other and a movable buffer plunger is reciprocally mounted in the open end of the elongated hollow interior of the buffer body. The movable buffer plunger is sized so that it does not come into operation until a predetermined amount of wear occurs at the firearm&#39;s gas port. In one embodiment a spacer member is provided to permit the buffer assembly to be used with a firearm having a full sized buttstock.

Description:
BACKGROUND OF THE INVENTION 
     Firearms that can fire automatically are designed so that they have a certain rate of fire. This rate of fire is selected in view of the intended mission or purpose for the firearm and the intended target. Consideration is also given to the intended accuracy, control of the firearm as well as ammunition consumption in selecting the rate of fire. Even though a firearm is designed for a certain rate of automatic fire, the actual rate of fire can change. This rate can be changed through the use of improper ammunition which can easily be cured by switching to the proper ammunition, but it can also change due to other factors that are are not easily cured. Unfortunately, the rate of fire of certain types of firearms can increase with use of the firearm. This usually results in a significant increase in the rate of fire of the firearm which results in undesirable consequences. These consequences can include inaccuracy, unreliable operation, stoppages, jams, struck cartridge cases, and overheating of the firearm. 
     This increase in the rate of fire due to continued firing of the firearm occurs commonly with certain gas operated firearms. The M-16 type of firearm, which includes the rather current M-4 version, have this increased rate of fire problem. These types of firearms tap the gas from the barrel and pass it back through a gas tube to operate the bolt mechanism. Unfortunately the gas port that taps the gas from the barrel becomes worn as the number of bullets forced through the barrel increases. This wear results in increased gas being ported through the gas tube and this results in an increase in the rate of fire. As a consequence, with time and the increase in the rounds fired and the number of bullets passing through the barrel the user of the firearm ends up with an unreliable firearm or possibly a firearm that is useless. When this occurs, the firearm must betaken out of service and subjected to a major overhaul that commonly will include replacement of the barrel and at least portions of the gas system. This is time consuming and is expensive. Due to this increase in the rate of fire problem, the effective service life of a gas operated firearm is limited. Consequently, a definite need exists to alleviate this increase in the rate of fire problem and to extend the length of the effective service life of the firearm. 
     There has been one attempt to alleviate this problem as indicated in U.S. Pat. No. 5,909,002. This patent, discloses a firearm buffer assembly that adds an additional moveable portion that is stated to increase the time the buffer assembly is in action and hence reduce the cyclic rate of fire of the associated firearm. However, this arrangement apparently has not been adapted to any extent. Possibly because this arrangement is fairly complex. Therefore, the need still exists for alleviating the increase in the rate of fire problem that does not require any significant alteration or reworking of the firearm so that the, firearm does not need to be withdrawn from service and subjected to undesired modification or reworking that involves significant time and expense. 
     This invention significantly reduces the rate of fire increase problem. Moreover, this invention not only reduces the rate of fire increase problem, but it also does this without requiring any reworking or modification of the firearm. Instead, all that is necessary is to replace the existing buffer assembly with the buffer assembly of this invention. This is easily accomplished in the field without withdrawing the firearm from service. Also, this replacement is easily accomplished by the user of the firearm without the need for any specifically trained personnel or any detailed instructions. 
     SUMMARY OF THE INVENTION 
     This invention relates to firearm buffers and more particularly to firearm buffers that are used with firearms that can be fire full automatically. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that controls the cyclic rate of full automatic fire of the firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that prevents the cyclic rate of automatic fire of the firearm from increasing. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that reduces the cyclic rate of full automatic fire of the firearm when the rate has exceeded the designed cyclic rate of full automatic fire of the firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire of the firearm. 
     It is an object of the the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the gas port wear caused by prolonged full automatic fire of the firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the early gas port wear that occurs in short barrel full automatic firearms. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the early gas port wear that occurs when the gas port is exposed to high pressure erosion during full automatic fire. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that can be used to retrofit existing firearms. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that requires no modification to the basic firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that replaces the current existing firearm buffer. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that is an easy replacement for the current existing firearm buffer. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that replaces the current existing firearm buffer without the use of any tools. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that replaces the current existing firearm buffer that does not require any special training for the replacement. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that replaces the current existing firearm buffer that does not require the withdrawal of the firearm from service. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that replaces the current existing firearm buffer that can be replaced by the user of the firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that does not adversely effect the operation of the firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that does not adversely effect semiautomatic operation of the firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that permits the use of a wider range of types of ammunition. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that increases the reliability of the firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that prevents or reduces jamming of the firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that prevents cartridge cases sticking in the chamber of the firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that prevents damage to the firearm. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that prevents breakage of firearm parts. 
     It is an object of the invention to provide a firearm buffer system for a firearm that: can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that is not temperature sensitive. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that is maintenance free. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that does not wear out. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that is simple in its operation. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that has a dual function. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic-fire that also prevents or reduces bolt or bolt carrier bounce. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that also uses live weights to prevent or reduce bolt or bolt carrier bounce. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that also uses live weights positioned for metal to metal impact to prevent or reduce bolt or bolt carrier bounce. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that compensates for the adverse effects of prolonged full automatic fire that also uses live weights positioned by springs for metal to metal impact to prevent or reduce bolt or bolt carrier bounce. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that reduces muzzle climb when fired fully automatically. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that is particularly useful for M-16 type firearms. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that is particularly useful for various versions of M-16 type firearms. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that is useful for various versions of M-16 type firearms having different buttstock configurations. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that is useful for various versions of M-16 type firearms having different buttstock configurations including the fixed buttstock version. 
     It is an object of the invention to provide a firearm buffer system for a firearm that can fire fully automatically that is useful for various versions of M-16 type firearms having different buttstock configurations including the carbine version. 
     These and other objects of the invention will be apparent from the following description of the firearm buffer system invention that includes a buffer assembly that has an elongated buffer body having an elongated hollow interior with a closed end and an open end, a plurality of weights sized and shaped to reciprocate in the elongated hollow interior of the buffer body, resilient means located in the elongated hollow interior of the buffer body for positioning at least some of the weights apart from each other and a movable buffer plunger reciprocally mounted in the open end of the elongated hollow interior of the buffer body. The buffer assembly has rate of full automatic fire control means for controlling the firearm rate of full automatic fire that is designed so that it does not operate until a predetermined high rate of fire is reached due to excessive erosion of the gas port of the firearm or from some other cause such as improper ammunition. In one embodiment a spacer member is provided to allow the buffer assembly to be used with a full sized fixed buttstock. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be hereinafter more fully described with reference to the accompanying drawings in which: 
     FIG. 1 is a side elevational view of a portion of an M-16 type firearm with a prior art buffer with portions broken away; 
     FIG. 2 is an enlarged view of a portion of the structure set forth in FIG. 1 illustrating gas port wear due to prolonged full automatic firing of the firearm; 
     FIG. 3 is a side elevational view of a portion of the M-16 type firearm set forth in FIG. 1 with the conventional buffer replaced by one embodiment of the firearm buffer system invention with portions broken away with the buffer assembly in the battery or forward position; 
     FIG. 4 is a side elevational view of the M-16 type firearm structure set forth in FIG. 3 with one embodiment of the firearm buffer system invention with portions broken away with the buffer assembly shown in the full recoil position; 
     FIG. 5 is an enlarged view of a portion of the structure illustrated in FIG. 4 taken within the circle  5  thereof; 
     FIG. 6 is a side elevational view of the M-16 type firearm structure set forth in FIGS. 3 and 4 with one embodiment of the firearm buffer system invention with portions broken away as the buffer assembly is returning to the battery position during full automatic firing; and 
     FIG. 7 is a side elevational view of a portion of an M-16 carbine type firearm with another embodiment of the firearm buffer system invention with portions broken away. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a portion of a standard prior art M-16 type firearm that is designated generally by the number  10 . This M-16 type firearm  10  has a standard upper and lower receiver  12  and  14  with a standard bolt carrier  16  located in the upper receiver  12 . As illustrated in FIG. 1 along with FIG. 2, a conventional barrel  11  extends from the upper receiver  12  and the barrel  11  has a conventional gas port  13  and a conventional front sight assembly  15  is connected to the barrel  11 . In addition, a conventional gas tube  17  is operatively connected to the gas port  13  and a conventional hand guard assembly  19  surrounds a portion of the barrel  11 . A conventional buttstock assembly  18  is also connected to the lower receiver  14 . This assembly  18  has a conventional hollow receiver extension tube  20  that has its rear portion  22  connected to the buttstock  24  by the screw  26 . The hollow receiver extension tube  20  contains a conventional recoil spring  28  and a conventional buffer  30 . 
     The buffer  30  has a generally tubular hollow buffer body  32  with a closed forward enlarged end portion  34  that contacts the rear portion  36  of the bolt carrier  16 . This conventional buffer body  32  is sized and shaped for reciprocal movement within the hollow receiver extension tube  20 . The conventional buffer body  32  is made from a light weight aluminum alloy. This buffer body  32  has an enlarged flange portion  38  that contacts and serves as a seat for the forward portion  40  of the recoil spring  28  that surrounds the rearward portion  31  of the buffer body  32 . 
     A plastic bumper  42  is located in the open aft end portion  44  of the buffer body  32 . This bumper  42  is secured in place within the aft end portion  44  of the buffer body  32  by the pin  46  so that a rear bumper portion  48  extends outward beyond the aft end portion  44  of the buffer body  30 . This rear bumper portion  48  strikes the rear interior surface  50  of the receiver extension  20  when the buffer  30  is in the full recoil position. 
     As illustrated in FIG. 1, five identical weights  52  are located within the hollow interior of the buffer body  32  and there are identical resilient washers  54  located between adjacent weights  52  and between the forward weight  52  and the closed end  56  of the hollow interior of the buffer body  32 . The weights  52  and the resilient washers  54  are sized so that they are free to move within the hollow interior of the buffer body  32 . Due to the inertia of the weights  52  as the buffer  30  moves into the battery position, the weights provide a force that is intended to prevent bolt or bolt carrier  16  bounce and hence cut down on possible bolt bounce misfires. 
     FIGS. 3 through 6 illustrate one embodiment of the firearm buffer system invention that is designated generally by the number  57  that comprises a buffer assembly  58  and a spacer  59  and the firearm buffer system invention  57  is illustrated as it would be installed in the same conventional M-16 type firearm  10  illustrated in FIG. 1 in place of the conventional buffer  30 . The buffer assembly  58  includes a generally tubular hollow buffer body  60  with a closed forward enlarged end portion  62  that contacts the rear portion  36  of the bolt carrier  16 . this buffer body  60  is sized and shaped for reciprocal movement within the hollow receiver extension tube  20 . The buffer body  60  is made from steel rather than a light weight aluminum alloy as is the prior art buffer body  32 . The enlarged end portion  62  of the buffer body  60  serves as a seat for the forward portion  40  of the recoil spring  28  that surrounds the outer surface of the buffer body  60 . The buffer assembly  58  also includes a plastic plunger bumper  64  reciprocally located in the open aft end portion  66  of the buffer body  60 . This plunger bumper  64  is secured into place for reciprocal movement within the rearward portion  66  of the buffer body  60  by a pin  68  that fits through a slot  70  in the plunger bumper  64  so that an enlarged tapered rear bumper portion  72  extends outward beyond the aft end portion  74  of the buffer body  60 . Under certain circumstances, that will be hereinafter described, the flat rear plunger bumper portion  76  strikes a portion of the spacer  59  or the rear surface  50  of the receiver extension  20  when the buffer body  60  is in the full recoil position. 
     The buffer assembly  58  also includes three solid cylindrical tungsten weights  78 ,  80  and  82  located within the hollow interior  84  of the buffer body  60 . These weights  78 ,  80 , and  82  are each cylindrical shaped and have the same exterior dimensions and they are sized and shaped for reciprocal movement within the hollow interior  84  of the buffer body  60  when the plunger bumper  64  is secured in place by the pin  68  with part of its smaller diameter cylindrical portion  86  located in the aft portion  66  of the interior  84  of the buffer body  60 . The two weights  80  and  82  that are separated from the plunger bumper  64  by the weight  78  have respective identical circular cross section cylindrical blind holes  88  and  90  that centrally are located in the respective surfaces  92  and  94  of the weights  80  and  82  that face toward the enlarged end portion  62  of the buffer body  60 . These cylindrical holes  88  and  90  extend to a depth approximately equal to ⅔ of the length of the weights  80  and  82 . A coil compression spring  96  has a portion thereof located within the hole  88  and another coil compression spring  98  has a portion thereof located within the hole  90  in the weight  82 . One end  100  of the coil spring  96  pushes against the bottom surface  102  of the hole  88  and the other end  104  of the spring  96  pushes against the surface  106  of the weight  82 . 
     In a similar manner, one end  108  of the coil spring  98  pushes against the bottom surface  110  of the hole  90  and the other end  112  pushes against the surface  114  of the hollow interior of the buffer body  60 . The coil spring  98  is longer and stronger than the coil spring  96  and this keeps the weights  80  and  82  spread apart and apart from the surface  114  within the hollow interior of the buffer body  60 . The purpose of these springs  96  and  98  is to maintain the weights  80  and  82  separated apart within the hollow interior of the buffer body  60 . The length of the slot  70  is substantially 0.325 of an inch and this permits the plunger bumper  64  to move inward into the aft end portion  74  of the buffer body  60  for up to 0.20 of an inch in the preferred embodiment. 
     The buffer system  57  also includes another very important component of the invention that is necessary for the standard full size M-16 type buttstock. This important component of the firearm buffer system  57  is the spacer member  59  that comprises a generally cylindrical shaped plastic elongated member that has a uniform cylindrical body portion  118  that is sized and shaped to slide into the interior  120  of the aft end portion  122  of the conventional M-16 type recoil spring  28 . This spacer member  59  has an enlarged circular radial flange  124  near its aft end  126  and the spacer member  59  also has a reduced diameter short cylindrical portion  127  at its aft end. As indicated in FIGS. 3,  4  and  6 , the cylindrical body portion  118  of this spacer member  59  fits into the interior  120  of the aft end portion  122  of the conventional recoil spring  28  and the flange  124  contacts the aft end portion  122  of the recoil spring  28  and this prevents the spacer member  59  from sliding forward into the interior  120  of the recoil spring  28 . This spacer member  59  contracts the plunger bumper  64  and permits it to function in a manner that will hereinafter be described in detail. 
     The manner in which the buffer system invention  57  functions will be described by referring sequentially to FIGS. 3 through 6. In FIG. 3, the firearm buffer assembly  58  is illustrated in the battery position or the position it would be at when the M-16 type firearm  10  is ready to fire with the bolt carrier in  16  located in its forward position. In this position, the end surface  129  of the buffer body  60  that has the enlarged end portion  62  rests against the rear surface  128  of the bolt carrier  16  in a manner similar to that for the conventional buffer  30  illustrated in FIG.  1 . When the M-16 type firearm  10  is fired the bolt carrier  16  will move toward the rear of the firearm  10  and into the hollow receiver extension tube  20  in a conventional manner and since the rear surface  128  of the bolt carrier  16  is in contact with the end surface  129  of the buffer body  60 , the bolt carrier  16  will push the buffer assembly  58  toward the rear portion  22  of the hollow receiver extension tube  20 . However, since the buffer body  60  is made from steel and since there are three tungsten weights  78 ,  80  and  82  located inside the buffer body  60 , the recoiling bolt carrier  16  will have to overcome the extra amount of inertia caused by this additional weight, identified by W and an arrow in FIG. 3 that works against the rearward movement of the bolt carrier  16  and this will cause a delay in rearward recoil movement of the bolt carrier  16  and hence contribute to a decrease in the cyclic rate of fire of the firearm  10 . When the inertia represented by W of the buffer assembly  58  is overcome, the buffer assembly  58  will be pushed into the hollow receiver extension tube  20  and at the same time the recoil spring  28  will be compressed. 
     As the recoil movement of the bolt carrier  16  continues it will reach its full recoil position and at the same time the adjacent buffer assembly  58  will also be the full recoil position which is illustrated in FIG.  4  and in FIG. 5 the enlarged view of a portion of FIG.  4 . Actually, there are various possible recoil positions for the buffer assembly  58  and two of these are illustrated in FIGS. 4 and 5 where two positions of the plunger bumper  64  of the buffer assembly  58  are illustrated. The position of the buffer assembly  58  within the hollow receiver extension tube  20  depends upon the condition of the gas port  13  of the barrel  11  that is best illustrated in FIG. 2 that shows the unworn or new gas port in solid lines  13  and the badly worn gas port in dashed lines  134  that has been enlarged in FIG. 2 for clarity. The position of a portion of the buffer assembly  58  in the full recoil position when the firearm has a normal substantially unworn gas port  13  is illustrated in dashed lines in FIGS. 4 and 5. As indicated by the dashed lines in FIG.  4  and also in greater detail in FIG. 5, the outer end  76  of the plunger bumper  64  does not come into contact with the outer end  132  of the cylindrical body portion  118  of the spacer member  59 . Instead, as indicated, there is a distance represented by the letter D between the outer end  76  of the plunger bumper  64  and the outer end  132  of the cylindrical body portion  118  of the spacer member  59 . This distance should be between 0.015 and 0.025 of an inch or the equivalent in metric units. In the preferred embodiment the distance D is 0.020 of an inch or the metric equivalent. Both the spacer member  59  and the buffer assembly  58  are designed and sized to achieve this desired distance D that is critical for the proper functioning of the firearm buffer system invention  57  in reducing the high rate of fire of the firearm when the gas port becomes excessively worn as illustrated for the worn gas port  134  in FIG.  2 . 
     When the gas port  13  of the firearm  10  becomes excessively worn as illustrated in FIG. 2 by the number  134 , this increases the amount of gas passing through the gas tube  17  and impinging upon the bolt carrier  16 . This results in increased energy being imparted to the bolt carrier  16  that is in turn imparted to the buffer assembly  58 . This increased energy results in the buffer assembly  58  moving further into the receiver extension tube  20  when the buffer assembly  58  is in the full recoil position which is indicated in FIGS. 4 and 5 by the full lines of the plunger bumper  64  of the buffer assembly  58 . As illustrated in FIGS. 4 and 5, in solid lines associated with the position due to the worn gas port  134 , the outer end  76  of the plunger bumper  64  comes into contact with the outer end  132  of the cylindrical body portion  118  of the spacer member  59 . When this occurs, the buffer assembly  58  continues to move in recoil due to the gases passed through the worn gas port  134  since the plunger bumper  64  is movable into the buffer body  60 . This additional movement due to the movable plunger member  64  into the buffer body  60  adds time to the recoil cycle that would not be present if the plunger bumper  64  was fixed to the buffer body  60  of the bumper assembly  58 . In addition, inward movement of the plunger bumper  64  into the buffer body  60  of the buffer assembly  58  is resisted by the inertia I of the heavy tungsten weights  78 ,  80  and  82  and this also adds an additional amount of time to the recoil cycle that would not be present if the plunger bumper  64  was not movable and if the heavy tungsten weights  78 ,  80 , and  82  were not present 
     FIG. 6 illustrates the firearm buffer system  57 , set forth previously in FIGS. 3 through 5, as the buffer assembly  58  is returning to the battery or firing position. As indicated previously, as the bolt carrier  16  of the M-16 type firearm  10  goes into the battery or firing position it has a tendency to bounce or move backward slightly after it hits its fully seated position. This causes problems by producing misfires. However, with this buffer assembly  58  this problem is alleviated since the spaced apart tungsten weights  78 ,  80  and  82  impart successive forward blows to the buffer body  60  that are in turn transmitted to the bolt carrier  16  that overcome or counteract any rearward bolt carrier  16  bounce movements or movements of the bolt carrier  16  toward the buffer assembly  58 . The fact that the weights  78 ,  80  and  82  are made from tungsten also increases their effectiveness since they impart significant blows to the bolt carrier  16  due to their weight. The springs  96  and  98  are important since they maintain the weights  80  and  82  in a separated relationship and this results in successive blows being transmitted to the bolt carrier  16  rather than just one. Moreover, the use of plastic spacers  54  between the weights in the prior art buffer  30  as illustrated in FIG. 1 has been eliminated and this results in sharp un-cushioned blows by the weights  78 ,  80  and  82  to the bolt carrier  16  that impart significantly more effective blows to the bolt carrier  16  than the prior art cushioned blows. 
     FIG. 7 illustrates the carbine version of the M-16 firearm that is designated generally by the number  136 . The M-16 carbine firearm  136  is the same as the previously described M-16 type firearm  10  except that it has a different receiver extension  142  and a different buttstock assembly that is collapsable that has been omitted for clarity since it is conventional and not necessary for a proper understanding of the invention. The hollow receiver extension  142  of the M-16 carbine  136  is shorter than the receiver extension  20  of the previously described M-16 type firearm  10 . In view of the shorter receiver extension  142  a slightly modified firearm buffer system invention  57  is used with this M-16 carbine  136 . With this firearm buffer system invention  57  in FIG. 7, all that is required for the M-16 carbine  136  is to omit the use of the spacer  59 . With the spacer  59  omitted, the buffer assembly  58  cooperates directly with the rear inside surface  144  of the receiver extension  142  of the M-16 carbine  136  as if the surface  144  was the same as the outer end  132  of the cylindrical body portion  118  of the spacer member  59 . 
     In this connection, the buffer assembly plunger bumper  64  is illustrated in dashed lines in FIG. 7 in the full recoil position with an unworn gas port  13  and the same distance D1 is present between the surface  144  and the outer end  76  of the plunger bumper  64  as the distance D between the outer end  76  of the plunger bumper  64  and the outer end  132  of the cylindrical body portion  118  of the spacer member  59 . As indicated previously, this distance D1 should be between 0.015 and 0.025 of an inch or the equivalent in metric units. In the preferred embodiment the distance D1 is 0.020 of an inch or the metric equivalent. The buffer assembly  58  is suitably sized to achieve this desired distance D1 that is critical for the proper functioning of the buffer invention  58  in reducing the high rate of fire of the firearm when the gas port becomes excessively worn as illustrated for the worn gas port  134  in FIG.  2 . 
     The function of the buffer assembly  58  in the M-16 carbine  136  is exactly the same as with the previously described M-16 type firearm  10  as described with respect to FIGS. 3 through 6. The only difference is that the shorter receiver extension  142  eliminates the need for the spacer  59  and the surface  144  of the shorter receiver extension  142  takes the place of the spacer member  59  end surface  132 . 
     Although the invention has been described in considerable detail with reference to certain preferred embodiments, it will be understood that variations or modifications may be made within the spirit and scope of the invention as defined in the appended claims.