Patent Abstract:
A buttstock assembly configured to work in conjunction with a compact buffer assembly consisting of a buffer tube, spring and bolt carrier with an integral buffer is provided. The buttstock assembly, buffer tube and bolt carrier are configured to work with AR15/M16 type firearms and their derivatives. By incorporating the buffer onto the bolt carrier, which is used in conjunction with a buffer tube of reduced length, the overall length of the host firearm is reduced by approximately 3.2 inches. No permanent modification need be made to the host firearm in order to utilize the compact buffer assembly and buttstock assembly disclosed herein.

Full Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates in general, to gas-operated firearms. More particularly, the present invention relates to the buffer system and buttstocks of autoloading firearms in the AR15/M16/M4 series of firearms. 
         [0003]    2. Description of the Related Art 
         [0004]    Militaries worldwide rely on a variety of firearms for both defensive and offensive purposes. In general, these firearms are divided into various subcategories based on the firearms structural features and the ammunition type used. Example categories include, but are not limited to, handguns, submachine guns and rifles. All three listed categories of weapons are often issued as the primary individual weapon for soldiers or police forces, based on the task the user is expected to perform. 
         [0005]    Handguns and submachine guns are selected because they are light and compact. Their diminutive size allows for easy transportation, deployment and use within a vehicle while their weight makes them ideal for daily carry. The submachine gun, while being slightly more obtrusive than the handgun, increases the firepower and hit probability of the user. Hit probability is primarily increased due to the user having three points of contact with the weapon, compared to only having two points of contact as is the case with a handgun. 
         [0006]    The buttstock present on many submachine guns offers a unique point of contact between the user and the firearm, a well known advantage. Handguns and submachine guns fire ammunition cartridges typically associated with handguns, so called pistol ammunition. Handgun cartridges such as 9 mm, .40S&amp;W and 45ACP offer acceptable terminal performance when compared against many other handgun cartridges, but offer poor performance when measured against typical rifle cartridges such as 5.56×45 mm (5.56 mm) and 7.62×51 mm (7.62 mm) ammunition. Additionally, a handgun&#39;s optimal performance range is 25-50 yards while a submachine gun using similar ammunition may extend the effective range of the cartridges out to 100-150 yards. The effective range is dependent on which specific handgun cartridge is being used. It must be noted that while a handgun cartridge being fired from a submachine gun may have an effective range up to 150 yards, meaning it is capable of sufficiently penetrating the target, it will generally have poor terminal performance on the intended target at that range. 
         [0007]    This poor terminal performance is because most defensive handgun ammunition uses hollow point bullet construction, or other expanding design, which will not expand consistently past 25-50 yards due to a lack of velocity. Handgun ammunition is also generally deficient in penetrating intermediate barriers such as wood, auto bodies and laminate glass while at the same time remaining terminally effective at all but the closest ranges, i.e. 25 yards and less. 
         [0008]    The next class of firearms is rifles, a class often subdivided into carbines and rifles based on barrel length and other characteristics of the firearm. For the purpose of this disclosure the term “rifle” will include carbines unless otherwise noted. Rifles are the primary armament of militaries worldwide. An example rifle would be the M16/M4 family of firearms and many of its derivatives such as the M6 piston driven design produced by LWRC International. Rifles typically have an effective range exceeding 600 yards. Rifle cartridges such as the 5.56 mm and 7.62 mm offer drastically increased intermediate barrier penetration, terminal performance, and superior external ballistics characteristics when compared to any handgun cartridge. The down side to a rifle is typically its overall length and to a lesser extent, its weight. Size restrictions make it difficult for tank and aircraft crews for example, to carry a rifle. This often leaves people confined to tight quarters armed with submachine guns at best, or pistols at worst. Should these crews be required to deploy their weapons in a violent confrontation they will immediately be disadvantaged when confronted by enemy forces equipped with rifles, to include the ubiquitous AK47 frequently used by enemy forces. As such, there is a persistent need to provide a firearm which offers the terminal and external ballistics, and intermediate barrier penetration capabilities of a rifle but in a package which is no larger than a submachine gun. 
         [0009]    Attempts to provide a firearm which has the compact size of a submachine gun, capable of firing ammunition with terminal and external ballistic similar to a rifle have been made. Many of these designs are referred to as Personal Defense Weapons (PDW). Designs which try to incorporate all of these features have been around for many years. Many previous attempts to produce a PDW failed because the design relied on a proprietary ammunition cartridge, was insufficiently compact, non-ergonomic, or simply unreliable. It should be noted that PDWs for the purpose of this disclosure only includes those designs which are capable of firing what is generally considered rifle ammunition. PDW designs which fire handgun ammunition such as 9×19 mm, .40S&amp;W, .45ACP, FN 5.7 mm and HK 4.6 mm ammunition generally rely on operating systems which are not capable of firing traditional rifle ammunition. Further, such rounds do not have external or terminal ballistic characteristics comparable to conventional rifle ammunition and are not capable of satisfying the needs of many military and law enforcement end users. 
         [0010]    Without being an exhaustive list, the following U.S. patents disclose various features which are of importance for understanding the improvements provided by the invention as set forth herein. Neither of the two patents mentioned below are admitted to be prior art by the Applicant. 
         [0011]    U.S. Pat. No. 5,827,992 to Harris et al (Harris) has several inherent deficiencies in its design that are evidenced by the fact that it never experienced wide acceptance or adoption by any military or police forces. First among these is that the design relies on the use of a new cartridge, the 5.56×30 mm MARS as taught by Harris (see column 9, lines 29-62). Militaries and police forces are slow and often reluctant to adopt new proprietary cartridges due to logistics concerns, unknown terminal performance and cost. Second, Harris does not teach how to make an M16 type rifle capable of firing rifle ammunition that is sufficiently compact to meet the needs of modern end users. In particular, the buffer system so disclosed would not provide for an M16 type weapon having an overall length of 20″ or less when equipped with an 8″ barrel, a requirement for some government contracts. Third, to practice the invention as taught requires the production of a M16 type receiver which dimensionally deviates from the prior art. This would substantially increase the implementation cost of adopting such a design. 
         [0012]    U.S. Pat. No. 7,137,217 to Olson and Knight discloses a compact rifle design which relies on an entirely new gas operating system and ammunition cartridge. The proprietary nature of this new firearm, its ergonomics and operating system, and the unique ammunition it uses greatly diminishes the likelihood of its adoption by military or other government forces. 
         [0013]    Among military and police forces of the Western world, the AR15/M16 family of firearms and their derivatives, including indirect gas operated versions (piston designs), have been in use for many years. Western nations have trained millions of individuals in the use of these firearms, therefore creating a weapon based on the AR15/M16 design is desirable as the deployment cost resulting from the adoption of a modified weapon system based on the AR15/M16 will be minimal. In addition, designing a new compact weapon system which uses conventional rifle ammunition further reduces deployment cost and logistics concerns. 
         [0014]    Compact personal defense weapons based on the AR15/M16 family of firearms are prevalent throughout the prior art. The primary method of reducing the overall length of the rifle has been to reduce the length of the barrel and gas operating system. While this is a valid method of reducing overall length it is not without shortcomings. First, the barrel may only be shortened so much before the external and terminal ballistics characteristics of a rifle projectile are diminished. Second, the shortened barrel reduces dwell time, which is critical to the proper firing cycle of the host rifle. Dwell time is the time between the projectile passing a barrels gas port and when it exits the muzzle of the firearm. This is an important component to the proper function of the firearm. Third, the increased gas pressure generated by many of the prior art rifle designs results in a phenomenon known as bolt bounce. Bolt bounce occurs when the bolt carrier of an AR15/M16 rifle reciprocates so violently that upon its forward movement the bolt carrier bounces back from the chamber end of the barrel. This results in the bolt unlocking from the chamber extension and the bolt carrier absorbing a significant amount of the hammer&#39;s force, resulting in a failure to fire. To combat bolt bounce, numerous buffers have been designed that work with varying degrees of success. 
         [0015]    Even with a barrel of reduced length, the overall length of the AR15/M16 family of firearms is still restricted by the length of the prior art buffer tube, which is nearly ubiquitous throughout the art. 
         [0016]    Shown in Figure A is the prior art carbine buffer assembly used with the AR15/M16 family of firearms. The buffer assembly  300  includes a carbine length buffer tube  330 , spring  340 , bolt carrier  310 , bolt  311  and buffer  320 . The rear end of the bolt carrier  310  abuts the front of the buffer  320  when the host rifle is fully assembled. The buffer  320  is contained within the buffer tube  330  and the bolt carrier  310  within an upper receiver when in battery. The bolt carrier  310  (6.672″ long) and buffer  320  (3.245″ long) have a combined length of over 9.9″. While the carbine buffer tube  330  does not receive the entire length of the bolt carrier  310  during its reciprocating motion, the 7.19″ length of the prior art carbine buffer tube is required to facilitate sufficient rearward movement of the bolt carrier  310  and compression of the spring  340  for proper function of the host firearm. The spring  340  and buffer  320  are required to provide a surface and force which resists the rearward movement of the bolt carrier  310 . The weight of the buffer  320  is selected to minimize bolt bounce and assist in the proper operation of the gas operating system. As a result, the prior art carbine buffer assembly  300  adds a fixed amount of additional length to AR15/M16 type firearms so equipped. 
         [0017]    Therefore in consideration of what is available in the prior art, it would be desirable to have a PDW that uses conventional rifle ammunition, has a barrel long enough to provide terminal and external ballistic similar to a rifle and has an overall length similar to a submachine gun. Additionally, it would be desirable to incorporate the above features onto a firearm having minimal structural and operational differences as compared to the prior art M16/M4 family of firearms. 
       SUMMARY OF THE INVENTION 
       [0018]    In view of the foregoing, one object of the present invention is to overcome the shortcomings in the design of personal defense weapons as described above. 
         [0019]    Another object of the present invention is to provide a buffer assembly having a bolt carrier with a buffer integrated onto its rearward end. 
         [0020]    Yet another object of the present invention is to provide a buffer assembly in accordance with the preceding objects which includes a spring and buffer tube configured to receive and facilitate the reciprocating movement of the bolt carrier and buffer during operation of the host firearm. 
         [0021]    A further object of the present invention is to provide a buffer assembly in accordance with the preceding objects which is capable of facilitating proper reciprocating movement of the bolt carrier when the host firearm is firing rifle caliber ammunition. 
         [0022]    A still further object of the present invention is to provide a buffer assembly in accordance with the preceding objects which reduces the overall length of an AR15/M16/M4 type rifle as compared to a similarly equipped AR15/M16/M4 type rifles using the prior art buffer and buffer tube assembly. 
         [0023]    Another object of the present invention is to provide a buffer assembly in accordance with the preceding objects which can be installed on prior art AR15/M16 type firearms without modification of the receiver assembly. 
         [0024]    Yet another object of the present invention is to provide for an adjustable buttstock which is capable of operating while attached to a buffer assembly produced in accordance with the preceding objects. 
         [0025]    In accordance with these and other objects, the present invention is directed to a buffer assembly and buttstock for use with gas operated firearms, particularly those of the AR15/M16/M4 variety, which is configured to reduce the overall length of the host firearm. This buffer system can be retrofitted to an existing AR15/M16/M4 type firearm without the need for any modification to the receiver of the firearm. 
         [0026]    The compact buffer assembly provided for herein includes a buffer tube, spring, bolt carrier with an attached buffer and a buttstock assembly. The bolt carrier is generally cylindrical in shape, incorporates a boss about the rear end and has been reduced in length as compared to those found in the prior art. Further, the rear of the bolt carrier has been constructed to receive a portion of the spring and thereby prevent the spring from binding during the bolt carrier&#39;s reciprocating movement. A two part buffer has been incorporated onto the rear end of the modified embodiment bolt carrier. The two portions of the buffer are welded together once installed onto the bolt carrier. By integrating the buffer onto the bolt carrier the overall length of these two components is reduced. This reduction in length facilitates a reduction in the length of the buffer tube thereby making the entire buffer assembly more compact. 
         [0027]    In addition, the bolt carrier/buffer combination provides sufficient mass to prevent bolt bounce from occurring, even when a short barrel is used in conjunction with the buffer assembly. 
         [0028]    Still further, the present invention reduces the overall length of an equipped firearm by at least 3.2 inches when compared against the prior art. 
         [0029]    These together with other improvements and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being made to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The novel features believed to be characteristic of the invention, together with further advantages thereof, will be better understood from the following description considered in connection with the accompanying drawings in which a preferred embodiment of the present invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended to define the limits of the invention. 
           [0031]    Figure A is a perspective side view of the prior art buffer assembly which is comprised of a buffer tube, spring, and buffer shown with an AR15/M16/M4 type bolt and bolt carrier. 
           [0032]      FIG. 1  is a side perspective view of a buffer assembly including a bolt carrier with attached buffer, buffer tube and spring in accordance with the present invention. 
           [0033]      FIG. 2  is an exploded perspective view of a bolt carrier assembly including a bolt, a bolt carrier, and a buffer in accordance with the present invention. 
           [0034]      FIG. 3  is a side perspective view of one side of the bolt carrier with attached buffer included in the buffer assembly shown in  FIG. 1 . 
           [0035]      FIG. 4  is a side perspective view of another side of the bolt carrier with attached buffer included in the buffer assembly shown in  FIG. 1 . 
           [0036]      FIG. 5  is a perspective cutaway view of the bolt carrier shown in  FIG. 3 . 
           [0037]      FIG. 6A  is a perspective side view of a personal defense weapon equipped with a buffer assembly and buttstock in accordance with the present invention. 
           [0038]      FIG. 6B  is a side view of the firearm shown in  FIG. 6A . 
           [0039]      FIG. 6C  is another side view of the firearm shown in  FIG. 6A . 
           [0040]      FIG. 6D  is a front view of the firearm shown in  FIG. 6A . 
           [0041]      FIG. 6E  is a back view of the firearm shown in  FIG. 6A . 
           [0042]      FIG. 6F  is a top view of the firearm shown in  FIG. 6A . 
           [0043]      FIG. 6G  is a bottom view of the firearm shown in  FIG. 6A . 
           [0044]      FIG. 7  is a partial cutaway view of the firearm shown in  FIG. 6B  showing the bolt carrier with attached buffer as it sits in relationship to the buffer tube prior to firing the rifle. 
           [0045]      FIG. 8  is an exploded perspective view of the buffer shown in  FIG. 1 . 
           [0046]      FIG. 9  is a perspective side view of the buffer tube shown in  FIG. 1 , showing the opening into the interior bore  52  located on its front end. 
           [0047]      FIG. 10  is a perspective side view of the buttstock shown in  FIGS. 6A-C  and  6 E-G, including a housing, guide rods, and a shoulder piece in accordance with the present invention. 
           [0048]      FIG. 11  is a perspective cutaway view of buttstock assembly while secured about the buffer tube. 
           [0049]      FIG. 12  is an exploded rear perspective view of the buttstock housing and catch mechanism in accordance with the present invention. 
           [0050]      FIG. 13  is a perspective side view of a guide rod of the buttstock assembly as shown in  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0051]    In describing a preferred embodiment of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. 
         [0052]    The present invention is directed towards a compact buffer assembly for use with AR15/M16 type firearms to include, for example, the M4, AR10, SR25 and piston operated designs such as LWRC International&#39;s M6 series of rifles. As used herein, the phrase “bolt carrier group” and “bolt carrier assembly” are used interchangeably. 
         [0053]    Unless otherwise specified, the various components which make up the trigger mechanism, upper receiver assembly, lower receiver assembly, bolt and bolt carrier assembly are those found on prior art AR15/M16 type firearms. 
         [0054]    As used herein, the word “front” or “forward” corresponds to the end of the bolt carrier  20  where the bolt  11  is located (i.e., to the left as shown in  FIGS. 1-3 , &amp;  5 ); “rear” or “rearward” or “back” corresponds to the direction opposite the end of the bolt carrier  20  where the bolt  11  is located (i.e., to the right as shown in  FIGS. 1-3 , &amp;  5 ). The phrase “in battery” or “battery” refers to the position of readiness of a firearm for firing. 
         [0055]    As shown in  FIG. 1 , the present invention is directed to a compact buffer assembly, generally designated by reference numeral  10 , including a generally cylindrical bolt carrier  20  with an attached buffer  40 , a bolt  11 , a buffer spring  12  and a buffer tube  50  (e.g., approximately 3.9″ long) having an interior configured to receive a portion of the bolt carrier  20  therein. It will be understood that the buffer assembly  10  is intended to be employed with any of the various AR15/M16 type firearms; however with minor modifications, some of its features could be more widely used for other firearms as well. It will also be understood that the bolt carrier  20  with attached buffer  40  is housed within an upper receiver  81  of an AR15/M16 type rifle  80  (see  FIGS. 6A-6G  and  7 ). 
         [0056]    In  FIGS. 1-4 , an embodiment of the bolt carrier  20  is shown. The bolt carrier  20  is generally cylindrical in shape and includes a bore  30  which extends between its front end  31  and back end  32 , varying in dimension based on a specific region&#39;s function and the structure defined thereon. The bolt carrier  20  also includes a hammer clearance slot  26  which permits the hammer to extend into the bolt carrier  20  and strike a firing pin  13  positioned in a portion of the bore  30 . The firing pin  13  is retained in place through the use of a cotter pin  15 , also commonly referred to as a firing pin retaining pin. 
         [0057]    The exterior of the bolt carrier  20  includes an ejection port cover opener  28  which provides room for the ejection port cover to close and a cam slot  27  which provides a contained area for the cam pin  14  to rotate and thereby facilitate limited rotational and longitudinal movement of an attached bolt  11  (see  FIGS. 1 ,  2 ,  3  and  4 ). 
         [0058]    Located on the top surface of the bolt carrier  20  is an integral carrier key  29 . The general features and advantages of the integral carrier key  29  are described in U.S. Pat. No. 8,387,513, filed on May 14, 2010, entitled “Self Loading Firearm Bolt Carrier With Integral Carrier Key And Angled Strike Face”, by Jesus S. Gomez, Jason Miller, Robert S. Schilling, and Michael R. Llewellyn (hereinafter, “the Gomez et al application”), which is also owned by the assignee of the present application and is hereby expressly incorporated by reference as if fully set forth herein. 
         [0059]    As shown in the exploded view of the bolt carrier  20  and buffer  40  provided in  FIG. 2 , and the isolated views of the same shown in  FIGS. 3-4 , the buffer  40  is attached to the back end of the bolt carrier  20 . The bolt carrier  20  has a bore  21  through the interior of its back end which receives a portion of the buffer  40 . The buffer  40  consist of two parts, a bumper  41  with integral shaft  42  and a cylindrical weight  43  attached thereto. The method of attaching the weight  43  to the shaft  42  of the bumper  41  will be described more fully hereinafter. 
         [0060]    Horizontal side views of the bolt carrier  20  with attached buffer  40  are provided in  FIGS. 3 and 4 . The rear of the bolt carrier  20  has a boss  22  for contacting an interior portion  86  of the upper receiver  81  (see  FIG. 7 ), thereby providing support during its longitudinal movement therein. The boss  22  is generally cylindrical in shape having an outside diameter larger than the body portion of the bolt carrier  20 . The boss is also of sufficient diameter to make contact with the cylindrical interior of the buffer tube  50  ( FIGS. 1 and 7 ) to ensure that the bolt carrier  20  remains centered therein. The boss  22  defines a circular side wall  33  ( FIGS. 3-5 ) on its backside which occupies a plane perpendicular to the longitudinal axis of the bolt carrier. The general features and advantages of the boss  22  are described in a U.S. Pat. No. 8,375,616 filed on Dec. 10, 2008, entitled “Automatic Rifle Bolt Carrier with Fluted Boss”, by Jesus S. Gomez and Jason Miller (hereinafter, “the Gomez and Miller application”), which is also owned by the assignee of the present application and is hereby expressly incorporated by reference as if fully set forth herein. Also present on the rearward end of the bolt carrier is a guide rod portion  23  ( FIGS. 2-5 ) which is configured to engage with and support the buffer spring  12  (shown in  FIG. 1 ) as will also be described more fully hereinafter. 
         [0061]      FIG. 5  shows a cutaway view of an embodiment bolt carrier  20  with attached bolt  11 , firing pin  13 , and cam pin  14 . The bolt carrier  20  has an interior thru bore  21  extending between its rear end and the hammer clearance slot ( FIGS. 2-4 ) of sufficient diameter to facilitate the passage of the buffer&#39;s  40  shaft  42  portion. Further, the interior diameter of the thru bore  21  is smaller than the exterior diameter of either the bumper  41  or cylindrical weight  43  portions of the buffer  40 . There is a countersunk bore  24  about the front end of the thru bore  21  configured to receive a portion of the cylindrical weight  43  and resist its rearward movement. Located on the back end  32  of the bolt carrier  20  is an annular side wall  25  which a portion of the bumper  41  contacts during the buffer&#39;s  40  rearward movements. 
         [0062]    Views of a AR15/M16 type personal defense weapon (PDW), generally designated by reference numeral  80 , used with one embodiment of the buffer assembly  10  and buttstock assembly  90  are shown in  FIGS. 6A-6C ,  6 E- 6 G, and  7 .  FIG. 6A-6G  show various views of the personal defense weapon  80 , also referred to herein as a firearm, and the major components from which it is comprised. Specifically, the upper receiver assembly  81 , lower receiver assembly  83 , handguard  82 , flash hider  84  and buttstock assembly  90  are shown.  FIG. 7  shows a cutaway of the view illustrated in  FIG. 6B . This view shows the linear relationship between the barrel  85 , bolt carrier  20  with attached buffer  40 , buffer spring  12  (see  FIGS. 1 and 7 ), and the buffer tube  50 . When the bolt carrier  20  is in battery a majority of the bolt carrier  20  and buffer  40  are present within the interior portion  86  of the upper receiver  81 . A small portion of the buffer  40  extends into the buffer tube  50  (see  FIG. 7 ). The PDW illustrated is equipped with an 8″ barrel  85 , giving the firearm an overall length of approximately 20″. 
         [0063]    Shown in  FIG. 8  is the buffer  40  which generally consists of a cylindrically shaped weight  43  having an interior opening  44  there through and a bumper  41  portion having an integral shaft  42 . The distil end  45  of the shaft  42  is smaller in diameter than the rest of the shaft  42  and is constructed to be received within the interior opening  44  of the cylindrical weight  43 . The components which make up the buffer  40  are manufactured from tungsten steel, but other, metals, iron and steel alloys of sufficient weight/density would suffice. All components of the buffer  40  are weighted to reduce the occurrence of bolt bounce, to provide for proper dwell time and, in general, to facilitate the proper operation of the host firearm. The bumper  41  portion could have a softer material attached thereto to further buffer the firearms recoil cycle without departing from the scope of the claimed invention. 
         [0064]    The buffer spring  12  shown in  FIGS. 1 and 7  is a compression type spring having coils with a rectangular cross section. Alternatively, a traditional compression type spring with round coils could be substituted. In one embodiment, buffer spring  12  is manufactured from stainless steel but any material, such as chrome-silica, appropriate for use as a compression spring, is suitable. 
         [0065]    As noted earlier, the bolt carrier  20  is received within a buffer tube  50 , sometimes referred to as a receiver extension, which is shown in  FIGS. 1 ,  7 ,  9  and  11 . The buffer tube  50  has an opening  51  on its front end which leads to a circular interior bore  52  sized to contain a portion of the buffer spring  12  and receive a portion of the bolt carrier  20  when it is rearwardly displaced during operation of the host firearm  80 . The forward exterior of the buffer tube  50  body  54  is threaded  53  and constructed to be threadedly received within an interior opening present on the lower receiver  83 . The back end  55  ( FIG. 9 ) of the buffer tube  50  is closed on in the embodiment shown, alternate embodiments may have a small liquid drain hole (not shown). Located between the threads  53  on the front of the buffer tube  50  and the back end  55  of the buffer tube are two circumferential ridges  56 A and  56 B ( FIG. 9 ). The circumferential ridges have a larger outer diameter than the body  54  of the buffer tube  50  and are used to support the housing  91  portion of buttstock assembly  90  as shown in  FIG. 11 . 
         [0066]    The buttstock assembly  90  as shown in  FIGS. 6A-6C ,  6 E- 6 G,  7  and  10 - 11  is comprised of three main components, a housing  91 , shoulder stock  93  and two guide rods  92 A and  92 B (see  FIGS. 10 and 13 ). The exterior surface of the housing  91  is contoured and shaped to act as a cheek piece  97  or comb. The interior of the housing  91  defines a longitudinally extending circular bore  99  sized to receive the buffer tube ( FIG. 10 ). The interior bore  99  is specifically sized such that the circumferential ridges  56 A and  56 B of the buffer tube make contact with the interior bore of the housing  91  (see  FIG. 11 ). On the housing&#39;s  91  forward face is a protrusion  94  ( FIG. 10 ) which engages with an opening present on AR15/M16 type lower receivers  83  to prevent the unintentional rotation of the buttstock assembly when assembled therewith. The housing  91  also defines thereon three openings, an opening  95  which allows the threaded portion  53  of the buffer tube  50  to pass through and two smaller openings  96 A and  96 B, which receive and support a portion of each guide rod  92 A and  92 B respectively. The opening  95  is smaller in diameter than the interior bore  99  thereby creating an internal shoulder  100  between the two. 
         [0067]    Located along the bottom side of the housing  91  is a placement  114  with an opening  116  that houses a spring  118  biased catch  115  used to operate the buttstock assembly  90  ( FIG. 12 ). The opening  116  runs traverse to the longitudinal axis of the housing&#39;s  91  interior bore  99  and is in communication with an opening  119  configured to receive a roll pin  113  ( FIG. 12 ). The catch  115  consists of two openings  124  with a cylindrical body  123  portion extending therebetween ( FIG. 12 ). The cylindrical body  123  portion has a pressure pad  132  on the end opposite its distal end  134 . The pressure pad  132  is the portion of the catch  115  to which the user applies force in order to operate the mechanism. One side of each opening  124  defines a detent  117  portion which is configured to engage with the notches  120  and  121  found on each guide rod,  92 A and  92 B (see  FIGS. 12 and 13 ). The cylindrical body  123  of the catch  115  has a slot  125  therein constructed to receive a portion of the roll pin  113 . Located at one end of the catch  115  is a bore  133  configured to receive a roll pin  131  ( FIG. 12 ). Also provided is a spring  118 , and a head piece  127 . The head piece  127  has a generally cylindrical shape with a centrally placed, longitudinally extending aperture  128  through its center ( FIG. 12 ). There is also a gap  129  through a side body portion of the head piece  127 . Located at one end is a bore  130  configured to receive a roll pin  131 . 
         [0068]    To assemble the catch mechanism, the body portion  123  of the catch  115  is inserted through the central opening of the spring  118 . The distil end  134  of the catch  115  is then inserted into the aperture  128  of the head piece  127 , effectively capturing the spring  118  therebetween. Next, the bore  130  of the head piece  127  is aligned with the bore  133  of the body portion  123  then a roll pin  131  is pushed through both bores  130  and  133 , thereby securing the two pieces together. The catch  115 , with attached spring  118 , is then inserted into the opening  116  of the housing  91 . The catch  115  is oriented so that the bottom of each opening  124  is facing up (see  FIG. 12 ), thereby placing the slot  125  in alignment with opening  119 . A roll pin  113  is inserted through opening  119  into slot  125  in order to secure the catch  115  to the housing  91 . 
         [0069]    When the catch  115  is secured within the opening  116  provided on the housing  91 , the spring  118  is captured between the roll pin  113  and a lip  135  formed between the body  123  and detent portion  117  of the catch  115 . The spring  118  biases against the roll pin  113  when the pressure pad  132  of the catch  115  is actuated. In one embodiment, the housing  91  is constructed from aluminum. Alternatively, polymers or other suitable metals or metal alloys may be used. 
         [0070]    The shoulder stock  93  defines a front side  105  and a back side  106  with a bore  107  extended therebetween ( FIG. 10 ). The bore  107  defines a circular opening configured to receive the portion of the buffer tube  50  located between the back side  55  and the back face of circumferential ridge  56 B ( FIG. 11 ). There is a circumferential chamfer  108  located about the front side of the bore  107 . Also found on the front side  105  are two openings  110 A and  110 B each configured to receive the back end of a guide rod  92 A and  92 B, respectively ( FIG. 10 ). In one embodiment, shoulder stock  93  is manufactured from aluminum, but alternate embodiment configurations may be manufactured from polymers or other suitable metals without departing from the scope of this invention. 
         [0071]    The back side  106 , or butt, of the shoulder stock  93  is textured so as to provide a nonslip surface. Two side walls  113 A and  113 B are defined by the shoulder stock  93  ( FIG. 10 ). There is a rectangular shaped opening  126  through each of the side walls  113 A and  113 B which provide mounting points for a rifle sling ( FIG. 10 ). 
         [0072]    The guide rods  92 A and  92 B are elongated, generally circular shaped rods each having two approximately semi-circular notches  120  and  121  along one side (see  FIGS. 11 and 13 ). Also present is a bore  122  (see  FIG. 13 ) that runs transverse to the longitudinal axis of each guide rod  92 A and  92 B. This bore  122  is located near each guide rod&#39;s back end and is configured to receive a roll pin  109  (see  FIGS. 11 and 13 ). 
         [0073]    A portion of each guide rods  92 A and  92 B rearward end is received within a bore  110 A and  110 B found in the front side  105  of the shoulder stock  93  ( FIG. 10 ). The shoulder stock has two openings  112 , one opening  112  in communication with each bore  110 A and  110 B ( FIG. 10 ). The guide rods  92 A and  92 B are inserted into their respective bores  110 A and  110 B and are rotated until the bore  122  found on each guide rod  92 A and  92 B is aligned with the appropriate opening  112  of the shoulder stock  93  ( FIGS. 10 and 13 ). A roll pin  109  is inserted through the aligned bore  122  and opening  112  of each guide rod  92 A and  92 B thereby securing them in place ( FIGS. 10 and 11 ). In one embodiment, guide rods are manufactured from aluminum, but alternate embodiments could be manufactured from other light-weight and durable metal alloys. 
         [0074]    The shoulder stock  93 , with attached guide rods  92 A and  92 B, is slidably secured to the housing  91  as follows. Guide rod  92 A and  92 B are inserted within the longitudinally extending openings  96 A and  96 B of the housing respectively ( FIG. 10 ). The guide rods  92 A and  92 B will slide freely forward until the forward notch  120  of each guide rods is engage by the detent  117  portion of the spring  118  biased catch  115 , preventing further movement. This is referred to as the “first position” (see  FIG. 10 ) of the shoulder stock  93  and is typically used when firing the attached firearm. To further collapse the shoulder stock  93  and move between the first and second positions, the catch  115  is depressed thereby disengaging the detents  117  from the forward notch  120  of each guide rod  92 A and  92 B. With the detents  117  disengaged, the shoulder stock  93  and guide rods  92 A and  92 B may be pushed forward until the detents  117  of the catch  115  engages with the rearward notch  121 . This is referred to as the “second position” of the shoulder piece (see  FIG. 6B ). When the detents  117  engage with the rearward notches  121  of the guide rods, the bore  107  of the shoulder stock  93  also receives a portion of the buffer tube  50  therein. The second position of the shoulder stock  93  is typically selected when the host firearm is to be transported or stored. But, it is important to note that the second position of the shoulder stock  93  in no way inhibits the firearm from being used. To move the shoulder stock  93  back to the first position, simply pull on the shoulder stock and the detents  117  will slip out of the rear notch  121  of each guide rod  92 A and  92 B, allowing the shoulder stock  93  to extend until the detents  115  reengage with the forward notch  120  on each guide rod. 
         [0075]    The gap between the guide rods  92 A and  92 B, and by extension the openings  96 A and  96 B which receive them, has to be large enough for the guide rods to clear the back end portion of the lower receiver  83  as shown in  FIGS. 6A-6C ,  6 F and  6 G. 
         [0076]    To attach the buffer  40  to the bolt carrier  20 , the shaft portion  42  of the bumper  41  is pushed through the enclosed thru bore  21  located on the back end  32  of the bolt carrier  20 . The bumper  41  will come to rest against the annular side wall  25  located about the back end  32  of the bolt carrier  20  while the distil end  45  of the shaft  42  protrudes into the hammer clearance slot  26 . The distil end  45  of the shaft  42  is received by the interior opening  44  of the cylindrical weight  43 . The cylindrical weight  43  is then welded to the shaft  42 , thereby making the buffer  40  an integral part of the bolt carrier  20 . The cylindrical weight  43  is larger in diameter than the thru bore  21  housing the shaft  42 , but smaller in diameter than the countersunk bore where it is partially received during, at least, the forward movement of the bolt carrier  20 . Once welded in place, the buffer  40  still has a limited range of longitudinal movement within the thru bore  21  of the bolt carrier  20 . 
         [0077]    On the back end  32  of the bolt carrier  20 , extending between the boss  22  and the annular side wall  25  is the guide rod  23 . The guide rod is a portion of the bolt carrier  20  that is smaller in diameter than the boss  22 . The boss  22  defines a circular side wall  33  on its back side. The guide rod portion  23  of the bolt carrier  20  is constructed to be received within an interior portion of the buffer spring  12 , with the forward most portion of the buffer spring  12  abutting the circular side wall  33  defined by the boss  22 . The structure of the guide rod portion  23  prevents the buffer spring  12  from binding during operation. 
         [0078]    The exterior diameter of the buffer spring  12  is no larger in diameter than the major diameter of the boss  22 . This allows the boss  22  to be in direct contact with an interior portion  86  of the upper receiver  81  and the interior bore  52  of the buffer tube  50 , without the spring  12  generating additional undesirable friction. The buffer spring  12  is able to bias the bolt carrier  20  into battery by placing its force against the circular side wall  33  of the boss  22 . In addition, the guide rod portion  23  of the bolt carrier  20  helps to orient and keep the buffer spring  12  from binding up during the rearward movement of the bolt carrier  20 . 
         [0079]    To use the buffer assembly  10  with a firearm such as the PDW  80  shown in  FIGS. 6A-6G  and  7 , the following steps must be taken. Initially, the housing  91  of the buttstock assembly  90  is placed against the back end of the lower receiver  83  so that the protrusion  94  on its forward face  98  engages therewith. The buffer tube  50  is inserted through the interior bore  52  of the housing  91  and threadedly secured to the lower receiver  83 . The buffer tube  50  is rotated until the forward face of the circumferential ridge  56 A (see  FIG. 11 ) comes to rest against the shoulder  100  of the housing  91  thereby securing both the buffer tube and the housing of the buttstock assembly  90  to the lower receiver  83 . The circumferential ridges  56 A and  56 B support the housing of the buttstock. The shoulder stock  93  with attached guide rods  92 A and  92 B may then be secured to the housing  91  as described above. 
         [0080]    After the buffer  40  is secured to the bolt carrier  20  as described above, the buffer spring  12  is attached about the guide rod  23  portion of the bolt carrier  20 . When properly seated in place, the forward edge of the spring  12  will rest against the circular side wall  33  defined by the boss  22 . The guide rod portion  23  of the bolt carrier  20 , the bumper  41  and a portion of the buffer  40  shaft  42  will be contained within an interior opening defined by the spring&#39;s  12  coils. 
         [0081]    The bolt carrier  20  with attached buffer  40  and spring are inserted into an interior portion  86  opening of the upper receiver  81  as follows. The interior portion  86  opening is a longitudinally extending bore configured to receive and facilitate the reciprocating movements of the bolt carrier  20  during the operation of the firearm  80 . With the bolt carrier  20  seated in place, the spring  12  and a portion of the bumper will be protruding from the rearward end of the upper receiver  81 . The upper receiver  81  is then oriented such than the protruding spring  12  is in alignment with the interior bore  52  of the buffer tube  50  attached to the lower receiver  83 . The rearward end of the spring  12  followed by a portion of the bumper  41  slide into the buffer tube  50 . With the upper receiver  81  and lower receiver  83  now in operational orientation, the front take down pin  16 A and rear take down pin  16 B ( FIG. 6B ) are used to removably secure the two receivers together. 
         [0082]    Thus the assembly of a firearm  80  using the new buffer assembly  10  and buttstock assembly  90  has been described. By reversing the steps outlined above, the bolt carrier  20 , buffer  40 , spring  12 , and buttstock assembly  90  may be removed for routine maintenance and repair. 
         [0083]    In one embodiment, buffer assembly  10  provided herein reduces the overall length of the AR15/M16 firearm by approximately 3.29″. In alternate embodiments, the buffer assembly (and its individual components) could be dimensionally scaled up to work with AR15/M16/AR10 type firearms that rely on bolt carriers and buffer tubes of larger dimensions than those discussed herein in regards to the prior art. In doing so a proportionally smaller buffer assembly will be provided for such a firearm than is found in the prior art. 
         [0084]    While one embodiment of the bolt carrier  20  shown is configured for use with a piston operated AR15/M16 type rifle, a bolt carrier modified to work with a more traditional direct impingent gas operating system which relies on a gas tube could be substituted without losing the benefits of the invention described and claimed herein. 
         [0085]    A buffer retaining pin and a spring which biases it into place are common throughout the art as it relates to AR15/M16 type rifles. The buffer retaining pin is used to secure the separate buffer  320  within the buffer tube  330  (see Figure A) and facilitate the assembly of so equipped firearms. The buffer assembly  10  described herein does not need a buffer retaining pin. By incorporating the buffer  40  onto the rear of the bolt carrier  20 , a buffer retaining pin would serve no purpose. When assembling an AR15/M16 type rifle originally constructed to use a buffer retaining pin, the part should be omitted during the installation of the buffer assembly  10  described herein. 
         [0086]    In an alternate embodiment, the buffer  40  could be secured to the bolt carrier  20  by threadedly securing the cylindrical weight  43  to the shaft  42 . 
         [0087]    In still another alternate embodiment, the bolt carrier could be machined with the buffer  40 , or a similarly weighted structure, as an integral part of its back end  32 . 
         [0088]    In still yet another alternate embodiment, a modified buffer having a body portion configured to be received within the thru bore  21  formed on the back end of a bolt carrier  20  could be manufactured. The modified buffer could be retained in place by sandwiching it between the back end  32  of the bolt carrier and the front end of the buffer spring  12 . 
         [0089]    In a further embodiment, the catch  115  could omit one of the openings  124  and detents  117  found along its length to simplify the mechanism. 
         [0090]    In a still further embodiment, additional notches may be placed along the length of the guide rods  92 A and  92 B to provide for additional positions of adjustment, possibly making the stock more ergonomic for the user. 
         [0091]    The foregoing descriptions and drawings should be considered as illustrative only of the principles of the invention. The invention may be configured in a variety of shapes and sizes and is not limited by the dimensions of the preferred embodiment. Numerous applications of the present invention will readily occur to those skilled in the art. Therefore, it is not desired to limit the invention to the specific examples disclosed or the exact construction and operation shown and described. Rather, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Technology Classification (CPC): 5