Patent Publication Number: US-11662169-B2

Title: Bolt carrier and bolt for gas operated firearms

Description:
This Application is a Continuation of application Ser. No. 16/430,865 filed on Jun. 4, 2019, which is a continuation of U.S. application Ser. No. 15/596,834, filed May 16, 2017, now granted as U.S. Pat. No. 10,309,739, which is a divisional of U.S. application Ser. No. 14/470,513, filed Aug. 27, 2014, now granted as U.S. Pat. No. 9,658,011, which is a continuation of U.S. application Ser. No. 13/841,618, filed Mar. 15, 2013, now granted as U.S. Pat. No. 8,844,424, which is a continuation-in-part application claiming benefit of U.S. application Ser. No. 13/588,294, filed Aug. 17, 2012, now granted as U.S. Pat. No. 8,950,312, which claims priority under 35 U.S.C. 119(e) to U.S. provisional Ser. No. 61/524,500, filed Aug. 17, 2011, each of which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to gas-operated firearms and, more particularly, to an improved bolt and bolt carrier for use in such firearms. 
     Description of the Related Art 
     The AR15/M16 family of firearms and their derivatives, including all direct gas operated versions, have been in use by the military and civilian population for many years. An essential part of this firearm&#39;s design is the bolt carrier which typically includes a bolt mounted in the carrier for axial sliding movement and rotation, a firing pin slidably mounted within the bolt and bolt carrier for restricted reciprocating axial movement, and a cam pin for limiting relative rotation between the bolt and the bolt carrier. 
     The bolt carrier is generally cylindrical in shape with a longitudinally extending circular bore throughout its length. An elongated opening is provided in the top and bottom of the carrier to allow the hammer to extend into the interior of the bolt carrier and strike the firing pin. The carrier is received and housed within the firearms receiver with the front of the carrier housing the bolt. The upper surface of the carrier immediately adjacent the front face includes a flat shelf for engagement with a charging handle. About the exterior of the bolt carrier are a series of lands and accompanying grooves, usually four, which extend from the forward end of the bolt carrier rearwardly over a distance of about one half the length of the bolt carrier. There are openings on the bolt carrier to mount a gas key, an opening which serves as a gas receiving port and an opening to receive the cam pin. Typically the gas key is secured to the bolt carrier through the use of two screws while the firing pin is retained in place through the use of a retaining or cotter pin. 
     Like the bolt carrier, the bolt has a body that is generally cylindrical in shape and is provided with a circular bore throughout its length which is designed to accommodate a firing pin. Located radially about a forward portion of the bolt are a series of lugs and an extractor. The exterior of the bolt has a recess provided therein with an extractor bearing surface that houses the extractor. The forward end of the extractor includes a gripping element, or claw, which catches and holds onto the rim of the case head of an ammunition cartridge. 
     The extractor rotates about a pin received by both the bolt body and the extractor. Located at the rearward end of the extractor is a spring and internal buffer. The extractor spring and buffer press against the extractor bearing surface thereby resisting rotation of the extractor about its axis and facilitate the extraction of a used ammunition cartridge. 
     Present on the front face of the bolt is an ejector that is located opposite the side of the front face adjacent the extractor. The ejector consists of a spring-loaded pin which is retained in place on the bolt through the use of a roll pin. The ejector assists in pushing an ammunition cartridge away from the bolt face when the firearm is being fired or otherwise unloaded. 
     The bolt carrier group is responsible for stripping, chambering, locking, firing, extraction and ejection of ammunition cartridges for the host rifle. The energy to perform these functions is provided in the form of hot, expanding gases which travel through the host firearm&#39;s gas tube, through the gas key and into the bolt carrier. A secure union between the gas key and bolt carrier is important to the proper operation of a direct gas operated firearm. Should the gas key become loose or be removed, the associated firearm will not properly function due to resulting gas leakage. 
     As shown in  FIG.  25 A , the prior art method of attaching a gas key to the bolt carrier relies on two screws which are torqued and then staked in place. 
       FIG.  25 A  illustrates a prior art bolt carrier  60  which uses a separate gas key  61  that has an integral nozzle for communicating with the gas tube of the host rifle. The base of the gas key  61  is secured to the bolt carrier  60  through the use of two retention screws  66 . The retention screws are inserted through the openings  62  located on the base of the gas key  61  then threaded into the openings  65  located on the top surface of the bolt carrier  60 . This method is deficient as the max torque applied to the screws is not sufficient to prevent the screws  66  from becoming threadedly unsecured due to vibration and the heating/cooling cycle of the host rifle during normal operation. The result is gas leakage which decreases the reliability of the host rifle by causing extraction and feeding related malfunctions. 
     The retaining pin or cotter pin  64  found in the prior art is retained within an opening  63  that provides no method to orient the pin  64 . As a result the pin  64  can be placed either by the user, or through rotation occurring during normal use of the rifle, into a position which orients the thinnest profile of the cotter pin towards the firing pin. This deficiency in the prior art reduces the service life of the cotter pin  64  resulting in several critical issues. The cotter pin can become bent such that maintaining the rifle is difficult since the cotter pin should be removed to service the bolt and bolt carrier properly. Removing a bent cotter pin  64  through the provided opening  63  is difficult, often requiring tools such as pliers to accomplish. Once the cotter pin  64  is removed, the user must be able to reinsert the cotter pin  64  back into the opening  63  of the bolt carrier  60 . If the cotter pin  64  is bent, this operation is often virtually impossible. The cotter pin  64  can also break or bend sufficiently thereby rendering the rifle inoperable. The terms “cotter pin” and “retaining pin” are used interchangeably herein. 
     The prior art bolt has several points of deficiency. First, there are seven bolt lugs placed radially about the forward end of the bolt. These lugs are evenly spaced apart except for the gap created on the exterior of the bolt to accommodate the extractor, which gap is referred to herein as the extractor pocket. When the extractor pocket is machined, a portion of the bolt&#39;s face is removed, resulting in the case head of the cartridge not being fully supported (see  FIG.  25 B ). 
     Second, the lugs located on either side of the extractor pocket are not fully supported, rendering them the weakest lugs on the prior art bolt. As such, these two lugs experience the highest rate of failure. Further, the lugs themselves are machined with sharp edges or geometric corners about their exterior. These geometric corners often accumulate material stress which can result in micro fractures that limit the service life of the bolt. 
     Third, extraction of a spent cartridge by the extractor, extractor spring and buffer can be disrupted due to a variety of conditions including a fouled barrel chamber, an over pressured gas system, an improperly annealed cartridge rim, as well as others. To compensate for this deficiency, various remedies have been developed to include, for example, the use of o-rings which increase the force the extractor is capable of placing on the rim of an ammunition cartridge. 
     Fourth and fifth, problems persist with the present method of securing the gas key to the bolt carrier using two screws as described above, and with the method by which the cotter pin that retains the firing pin is able to rotate into a structurally weak position. Finally, there is a deficiency in prior art methods of manufacturing the bolt. It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, one object of the present invention is to overcome the shortcomings in the design of bolt carriers and bolts for self-loading firearms as described above. 
     Another object of the present invention is to provide a bolt carrier having an integral gas key with a removable nozzle which is constructed to be in communication with a gas tube of the host firearm. 
     Yet another object of the present invention is to provide a bolt carrier in accordance with the preceding objects in which the nozzle is threadedly secured to the gas key and held in place with a cross pin that relies on tension and the structure of the upper receiver to retain the cross pin in place. 
     A further object of the present invention is to provide a bolt carrier in accordance with the preceding objects in which the bolt carrier is constructed to orient the cotter pin that retains the firing pin such that the widest profile of the cotter pin is always oriented towards the firing pin. 
     A still further object of the present invention is to provide a bolt and bolt carrier in accordance with the preceding objects which includes a bolt with fully supported bolt lugs and an improved structure for incorporation of the extractor. 
     Another object of the present invention is to provide a bolt in accordance with the preceding objects in which the extractor engages a larger portion of the rim of the cartridge case as compared to prior art extractors. 
     A still further object of the present invention to provide an improved bolt carrier in accordance with the preceding objects that is not complex in structure and which can be manufactured at low cost but yet increases the reliability and safety of the firearm. 
     In accordance with these and other objects, the present invention is directed to a direct gas operated firearm of the AR15/M16 variety having an improved bolt carrier assembly. This improved bolt carrier assembly can be retrofitted to an existing direct gas operated AR15/M16 type rifle without the need for any modification to the receiver of the rifle or any other part thereof. 
     The improved bolt carrier includes an integral gas key which is threaded to receive an extension nozzle which is constructed to receive a portion of the host firearm&#39;s gas tube. The extension nozzle is held in place through the use of a cross pin which prevents loosening of the nozzle during use of the firearm. 
     The present invention also provides an improved bolt carrier that includes a machined structure on the exterior of the bolt carrier which optimally orients the cotter pin that retains the firing pin so as to maximize the service life of the cotter pin. In particular, the retaining pin is oriented in a vertical profile so that the widest profile of the retaining pin is always oriented toward the firing pin. 
     In addition, the improved bolt carrier according to one embodiment of the present invention has a bolt with a fully supported bolt face, eliminating the machining of a gap into the bolt face in order to accommodate an extractor. By fully supporting the bolt face, the lugs located on either side of the extractor pocket are not undercut, resulting in a more durable bolt. 
     Still further, one embodiment of the bolt includes an extractor having an extractor claw that grabs or engages approximately 17% more of an ammunition cartridge&#39;s rim as compared with prior art extractors. By spreading the forces related to extraction over a larger area of the rim of the cartridge, the likelihood of failed extraction is substantially diminished. 
     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 
         FIG.  1    is an exploded perspective view of a bolt carrier assembly including a bolt carrier, an extension nozzle, and a bolt in accordance with the present invention. 
         FIG.  2    is a side perspective view of the left side of the bolt carrier included in the bolt carrier assembly shown in  FIG.  1   . 
         FIG.  3    is a side perspective view of the right side of the bolt carrier shown in  FIG.  2   . 
         FIG.  4    is a perspective cutaway view of the bolt carrier shown in  FIG.  2   . 
         FIG.  5 A  is a top perspective view of the extension nozzle included in the bolt carrier assembly shown in  FIG.  1   . 
         FIG.  5 B  is a bottom perspective view of the extension nozzle shown in  FIG.  5 A , with the extension nozzle rotated 180 degrees about its longitudinal axis relative to the view shown in  FIG.  5 A , making the gas port visible. 
         FIG.  5 C  is a side perspective view of the extension nozzle shown in  FIG.  5 A  with the nozzle rotated 90 degrees from the position shown in  FIG.  5 B , making the opening for the roll pin visible. 
         FIG.  5 D  is a perspective cutaway view of the extension nozzle shown in  FIG.  5 C , showing the opening through the extension nozzle and the gas port. 
         FIG.  6    is a side perspective view of the right side of an AR15/M16 type rifle which is operated by direct gas impingement and suitable for use with the bolt carrier in accordance with the present invention. 
         FIG.  7    is a perspective cutaway view of the upper receiver used with the AR15/M16 type rifle shown in  FIG.  6   . 
         FIG.  8    is a perspective cutaway view of the bolt carrier shown in  FIG.  2    along with a portion of a gas tube of the host firearm. 
         FIG.  9    is a side perspective view of the bolt included in the bolt carrier assembly shown in  FIG.  1   . 
         FIG.  10    is an exploded perspective view of the bolt shown in  FIG.  9   . 
         FIG.  11    is an exploded view of the bolt shown in  FIG.  10    rotated 180 degrees; 
         FIG.  12    is a side view of the bolt shown in  FIG.  9   . 
         FIG.  13    is a cross sectional view of the bolt shown in  FIG.  12   . 
         FIG.  14 A  shows an elevated side view of an extractor for use with the bolt carrier assembly of  FIG.  1    in accordance with the present invention. 
         FIG.  14 B  shows a top perspective view of the extractor shown in  FIG.  14 A . 
         FIG.  14 C  shows a side cutaway view of the extractor shown in  FIG.  14 A . 
         FIG.  14 D  shows a bottom perspective view of the extractor shown in  FIG.  14 B . 
         FIG.  15 A  is a first distal end view of the bolt shown in  FIG.  9   . 
         FIG.  15 B  is a second distal end view of the bolt shown in  FIG.  15 A  with additional reference elements added to clarify structure. 
         FIG.  16    is a side perspective view of the bolt shown in  FIG.  9   . 
         FIG.  17    is a side perspective view of an alternate embodiment bolt in accordance with the present invention. 
         FIG.  18    is an exploded perspective view of the bolt shown in  FIG.  17   . 
         FIG.  19    is an exploded view of the bolt shown in  FIG.  18    rotated 180 degrees; 
         FIG.  20    is a side view of the bolt shown in  FIG.  17   . 
         FIG.  21    is a cross sectional view of the bolt shown in  FIG.  20   . 
         FIG.  22 A  shows an elevated side view of an alternate embodiment extractor for use with the bolt assembly of  FIG.  17    in accordance with present invention. 
         FIG.  22 B  shows a top perspective view of the extractor shown in  FIG.  22 A . 
         FIG.  22 C  shows a side cutaway view of the extractor shown in  FIG.  22 A . 
         FIG.  22 D  shows a bottom perspective view of the extractor shown in  FIG.  22 B . 
         FIG.  23 A  is a first distal end view of the bolt shown in  FIG.  17   . 
         FIG.  23 B  is a second distal end view of the bolt shown in  FIG.  23 A  with additional reference elements added to clarify structure. 
         FIG.  24    is a side perspective view of the bolt shown in  FIG.  17   . 
         FIG.  25 A  is a side perspective view of a prior art bolt carrier and gas key. 
         FIG.  25 B  is a top view of a prior art bolt face. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. 
     The present invention is directed towards a bolt and bolt carrier group or bolt carrier assembly for use with the M4/M16/AR15 family of firearms and their derivatives. As used herein, the phrases “bolt carrier assembly” and “bolt carrier group” are used interchangeably. 
     Unless otherwise specified, the various components which make up the trigger mechanism, upper receiver assembly, lower receiver assembly, buttstock assembly, bolt and bolt carrier assembly are those found on the prior art M4 and M16 family of firearms. 
     As used herein, “front” or “forward” and “distal” correspond to the end of the bolt carrier  20  where the gas key is located and nearest the muzzle of the firearm (i.e., to the left as shown in  FIGS.  1 ,  2  and  4   ); and “rear”, “rearward”, “back” or “proximal” correspond to the end of the bolt carrier  20  nearest the buttstock of the firearm and opposite the end where the gas key is located (i.e., to the right as shown in  FIGS.  1 ,  2  and  4   ). 
     As shown in  FIG.  1   , the present invention is directed to an improved bolt carrier assembly, generally designated by reference numeral  10 , including a bolt carrier  20  with an integral gas key  30 , a bolt  21  and an extension nozzle  50  coupled to the gas key with a roll pin  31 . It will be understood that the bolt carrier assembly  10  is intended to be employed with any of the various direct gas operated M16 type firearms; however with minor modifications, some of its features could be more widely used for other firearms as well. The features of the bolt  21  are capable of being adapted to work with most direct and indirect (piston operated) gas operated firearms. It will also be understood that the bolt carrier assembly  10  is housed within an upper receiver  13 , shown in  FIGS.  7  and  8   , of a M16 type rifle  300 . 
     As shown in the exploded view of the bolt carrier assembly  10  provided in  FIG.  1   , and the isolated views of the bolt carrier  20  shown in  FIGS.  2 - 4   , the integral gas key  30  is located on the top surface of the bolt carrier  20 . The gas key  30  has an opening  34  at its rearward end for the roll pin  31 , and a threaded opening  35  at its front end which interfaces with a threaded member  52  on the extension nozzle  50  as will be described more fully hereinafter. Horizontal side views of the bolt carrier  20  shown with the extension nozzle  50  threadedly retained in place and secured with the roll pin  31  are provided in  FIGS.  2  and  3   . The front end of the gas key  30  also has an indexing notch  33  that is used to orient the extension nozzle as will also be described more fully hereinafter. 
       FIG.  4    shows a cutaway view of the preferred embodiment bolt carrier  20  with the extension nozzle  50 . An opening  42  is machined into the top exterior of the gas block, through to the interior opening  24  for the bolt  21 . The through bore created by the machining process is generally referred to herein as a port  36 . The port  36  is angled along its length and allows for the flow of expanding gases to pass from the gas key  30  into the opening  24  behind the bolt  21 , thereby facilitating the operation of the rifle  300 . 
     Also present on the bolt carrier  20  is a hammer clearance slot  22 , which permits the hammer (not shown) to extend into the bolt carrier  20  and strike a firing pin  29 . An opening  41  for a cotter pin  40  and an opening  24  for a bolt  21  (shown in  FIGS.  1  and  9   ) are also provided within the bolt carrier. 
       FIGS.  1  and  2    show the opening  41  designed to contain the cotter pin  40 . The cotter pin  40 , also referred to as a retaining pin, is installed after the firing pin  29  is placed within the interior of bolt carrier  20 . The sole purpose of the cotter pin  40  is to retain the firing pin  29  within the bolt carrier  20 . The opening  41  is part of a bore which runs through the bolt carrier  20 , perpendicular to the longitudinal axis thereof. The bore connected to the opening  41  is constructed to accommodate the tail portion  46  of the cotter pin  40 . One end of the opening  41  is constructed to hold the head  45  of the cotter pin  40  in a vertical orientation as shown in  FIG.  1   , thereby orienting the widest profile of the tail portion  46  towards the firing pin&#39;s  29  annular flange  44 . From an external view, the opening  41  about the exterior of the bolt carrier  20  is approximately “T” shaped. As seen best in  FIG.  2   , the vertical portion of the opening  41  is for receiving the head  45  portion of the cotter pin  40 . The horizontal portion of the opening  41  is to facilitate the insertion of a tool, such as a small screw driver, bullet tip, pliers or their equivalent, to aid in the removal of the cotter pin  40 . By orienting the cotter pin  40  in this manner, the widest profile of the cotter pin  40  is oriented towards the rearward side of the annular flange  44  located near the back end of the firing pin  29 . This orientation with the largest profile of the cotter pin  40  facing the annular flange  44  of the firing pin  29  makes the cotter pin  40  better able to resist metal fatigue which reveals itself as the bending or breakage of the part. It should be understood that in alternate embodiments the opening  41  could be oriented to have an external appearance such as an “X”, a “+”, or other equivalent shapes and structures, so long as the cotter pin  40  is being oriented to expose the largest cross section of the tail portion  46  towards the annular flange  44  of the firing pin  29  and prevent the cotter pin  40  from unnecessarily rotating. 
     The opening  24  in the bolt carrier  20  for the bolt  21  includes a longitudinal bore which extends from the forward end of the bolt carrier  20  rearwardly for a distance sufficient to accommodate the rearward portion of the bolt  21 . A smaller bore  39  (see  FIG.  4   ) continues for a further distance to accommodate the rear end  81  of the bolt  21 . The top of the bolt carrier  20  immediately adjacent the front face thereof has a charging handle contact point  38  which facilitates manual operation of the host rifle  300 . 
     Located rearwardly of the charging handle contact point  38  is a cam slot  26  which provides a contained area for the cam pin  27  to rotate, thus allowing the bolt  21  to move rearward and rotate axially within the bolt carrier  20 . The cam pin  27  retains the bolt  21  within the bolt carrier  20 . 
     The bolt carrier  20  is also provided with a series of bearing surfaces  37 . These bearing surfaces  37  are located on the front half, top and bottom sides of the bolt carrier  20 , and are in direct contact with the interior of the upper receiver  13 . The bearing surfaces  37  located along the bottom portion of the bolt carrier  20  are interrupted along there length by a series of sand cuts  23 . The sand cuts  23  are longitudinal cuts, having a generally rectangular shape, which reduce the exterior dimensions of the bolt carrier&#39;s bearing surfaces  37  when present. If any foreign material, including material resulting from the discharge of a firearm, accumulates within the upper receiver  13 , the sand cuts  23  provide an exit for the accumulating debris. 
     The bolt carrier  20  is further provided with a series of flat surfaces  43  machined onto the forward portion of its exterior. These flat surfaces  43  are present on both the right and left sides of the bolt carrier  20  and machined so that they come to an apex  143 . The apex  143  at which point these flat surfaces  43  meet protrudes from the exterior of the bolt carrier  20 . These “flats”  43  provide additional space for the accumulation of debris. By providing space and egress points for the accumulation of debris, the static and kinetic friction forces between the bolt carrier  20  and the interior of the upper receiver  13  will not increase as rapidly during prolonged use of the host firearm. Also present is a door opener  28  which provides room for the door latch (not shown) to close. 
     As best shown in the isolated views in  FIGS.  5 A- 5 D , the bolt carrier assembly  10  includes an extension nozzle  50  having an indexing notch  51 , a threaded member  52 , an opening  53  and a port  54 . Once the threaded member  52  of the extension nozzle  50  is properly threaded with the threaded opening  35  in the gas block, the roll pin  31  is inserted through the opening  34  in the gas block  30  and an opening  53  through the extension nozzle thereby rotationally restraining the extension nozzle  50 . The purpose of aligning the indexing notches  51  and  33  is to ensure that the port  54  of the extension nozzle  50  is in communication with the port  36  through the gas key  30  (shown in  FIG.  8   ) thereby facilitating the proper operation of the host firearm. 
     More particularly, a top perspective view of the extension nozzle is shown in  FIG.  5 A , with  FIG.  5 B  being a bottom perspective view of the extension nozzle rotated 180 degrees about its longitudinal axis relative to the view shown in  FIG.  5 A , making the gas port  54  visible.  FIG.  5 C  is a side perspective view of the extension nozzle rotated 90 degrees from the position shown in  FIG.  5 B , making the opening  53  for the roll pin  31  visible. Finally,  FIG.  5 D  is a perspective cutaway view of the extension nozzle shown in  FIG.  5 C , showing the opening through the extension nozzle  50  and the gas port  54 . 
     A timing washer  32 , which is located between the extension nozzle  50  and the forward face of the gas key  30 , may be placed over the threaded member  52  of the extension nozzle  50  and used as a means to orient the extension nozzle  50  when it is threadedly secured to the gas block  30 . More particularly, a series of wrench flats  55  are provided about the exterior of the extension nozzle  50  and provide a means by which torque may be applied during installation of the extension nozzle  50 . A crescent wrench or a wrench of similar design is used to rotate the nozzle  50  by engaging with the wrench flats  55 . When the extension nozzle  50  is being threaded into the gas block  30 , the indexing notch  51  of the extension nozzle  50  is aligned with the indexing notch  33  of the gas key  30 . The timing washer  32 , which allows for a predetermined torque value to be applied, is selected during assembly to facilitate alignment of the two separate indexing marks  33  and  51  and application of the proper torque range. The timing washer  32  is machined from stainless steel but other materials suitable for use in the manufacture of washers would also be acceptable. Alternatively, modern manufacturing techniques and technologies make it possible to time the threads, thereby eliminating the need for a timing washer  32 . 
     Another method of securing the extension nozzle  50  to the gas block  30  includes press fitting them together. This can be achieved by manufacturing an extension nozzle  50  without a threaded member and a gas block which has a non-threaded opening. The threaded portion of the threaded member  53  shown in the illustrated embodiment would be replaced by a smooth exterior, shaped to be received by the non-threaded opening in the gas block. Such a non-threaded extension nozzle would need to be manufactured such that it required substantial force to be pressed into the opening of the gas block. Once pressed into place, the extension nozzle could then be further secured into place through the use of a roll pin such as roll pin  31  or alternatively, welded. 
     The roll pin  31  used to assist in securing the extension nozzle  50  to the gas key  30  may, alternatively, be replaced with a non-tensioning type (i.e. dowel pin). This solution works because the gas key  30  of the bolt carrier  20  rides in a channel  14  (shown in  FIG.  7   ) within the interior of the upper receiver  13 . The location of the gas key  30  within this channel  14  retains the dowel or roll pin because there is insufficient space between the exterior of the gas key  30  and the walls of the channel  14  for the roll pin  31  to fall out. 
       FIG.  6    illustrates a perspective side view of a direct gas operated rifle  300 , generally consisting of an upper receiver group and a lower receiver group. The lower receiver group, well known in the prior art, generally consists of a lower receiver  15  with internal operation control components, a buffer tube and buttstock  16 . The upper receiver group generally consists of an upper receiver  13 , a barrel  12 , and a set of handguards  17 , all well known throughout the prior art. 
       FIG.  7    shows a side cutaway view of the upper receiver  13  in which the channel  14  in which the gas key  30  rides is visible. The channel  14  is generally rectangular in shape and constructed to allow for the longitudinal travel of the gas key  30  and other attached components. The channel  14  is narrow enough to prevent the roll pin  31  holding the extension nozzle  50  from falling out of the opening  34  which is designed to house it. Thus the channel passively assists the roll pin  31  in securing the extension nozzle  50  onto the gas key  30 . 
       FIG.  8    shows a side cutaway view of the bolt carrier  20  and extension nozzle  50 . This view illustrates the gas tube  11  of the host firearm being received by and in operational contact with the opening at the forward end of the extension nozzle  50 . In the illustrated embodiment, the opening at the forward end of the extension nozzle  50  has been provided with a 60-degree chamfer to ease its acceptance of the gas tube  11 . When the rifle  300  is discharged, gas travels through the gas tube  11  into the opening  56  of the extension nozzle  50 , exiting the port  54  (see  FIGS.  5 B and  5 D ) located at the rear of the extension nozzle  50 , into the port  36  which travels through the gas key  30  arriving at the rear portion of the opening  24 , which houses the bolt  21 , where the expansion of the gas causes the bolt carrier  20  to move rearward. After a round of ammunition has been fired the bolt carrier group  10  is only able to move rearwardly when the chamber pressure of the barrel  12  decreases sufficiently, thereby allowing the bolt  21  to rotate and disengage from the barrel extension (not shown). 
     The incorporation of the port  36  through the interior of the bolt carrier  20  is a significant feature related to its manufacture. The bolt carrier  20 , in general, is manufactured through the use of lathes and mills to create its general shape along with both its internal and external structures. The bolt carrier may also be cast, with secondary machining operations being performed to bring critical surfaces within the required specifications. After the integral gas block  30  is machined onto the exterior of the bolt carrier  20 , a drill press, mill or similar machine is used to machine the opening  42  into the top exterior of the gas block, through to the interior opening  24  for the bolt  21 . As previously noted, the resulting port  36  is angled along its length. After the port  36  is drilled, the opening  35  at the forward end of the gas block  30  is threaded to receive the extension nozzle  50 . 
     The bolt  21  of  FIG.  1    is shown in greater detail in  FIGS.  9 - 13  and  15 A,  15 B and  16   . The bolt  21  is comprised of an elongated body having a rear end  81  and a front end  82  located along a longitudinal axis. Located about the rear end  81  of the bolt  21  are two circumferential flanges  83  which occupy parallel plains leaving a space, or groove  84 , therebetween. The groove  84  is formed to accept a series of gas sealing rings  85 . The bolt  21  is formed with a neck portion  86  extending between the annular flanges  83  and the cylindrical body  87 . The cylindrical body  87  of the bolt defines a first bore  88  and a second bore  89 , both of which extend through the cylindrical body  87  of the bolt  21 . In the interior of the bolt  21 , there is formed a longitudinal bore  90  which receives the firing pin  29 . The cylindrical body  87  also defines an exterior surface  91  thereabout. The face portion  92  of the bolt  21  serves as a cartridge bearing surface  92  and is located near the front end  82 . A separate structure but integral feature of the bolt face  92  is the circumferential groove  162  present on the exterior portion of what defines the bolt face  92  (shown in  FIGS.  15 A and  15 B ). The circumferential grove  162  is present to facilitate the accumulation of debris incidental to the firing of the associated indirect gas operated rifle  300  (see  FIG.  6   ). In addition, the circumferential groove  162  about the bolt  21  face  92  relives material stress. 
     The cylindrical body  87  portion of the bolt  21  defines an extractor recess  93 . The extractor recess  93 , formed on the exterior surface  91 , is in communication with the longitudinal bore  90 , or firing pin bore. A bearing portion  94  for the extractor  80  resides within the extractor recess  93  and is integrally formed with the body  87  of the bolt  21 . The extractor bearing portion  94  of the recess  93  includes a mating surface  96  (see  FIG.  13   ) defining a curved plane substantially parallel to the exterior surface  91  of the bolt  21  such that the face  92  is circular. The underside  95  of the extractor  80  is also curved so that it may engage with and rest against the mating surface  96 . 
     The extractor is shown in  FIGS.  14 A- 14 D . The rearward end of the extractor  80  defines a flange  104  which serves as a bearing surface for the extractor springs  101  (see  FIG.  10   ). Located on the flange  104  are two nipples  103  each of which individually engage with a portion of an extractor spring  101 . 
     The extractor body  105  extends between the flange  104  and the extractor claw  106 , located on the extractor&#39;s forward end  108 . The extractor body  105  defines a pin receiving portion  99  along its length. The pin receiving portion  99  is a bore that runs perpendicular to the longitudinal axis of the extractor  80 . The extractor claw  106  defines a recess  109  having an upper portion or lip  107 . The lip  107  portion of the extractor claw  106  is constructed to engage with the rim of an ammunition cartridge. Structurally, the lip  107  portion of the extractor claw  106  is wider than the extractor body  105 . Further, the circumferential edge  110  of the lip  107  comes to two forward edges  111  which are located on opposite sides of the extractor claw  106 . The extractor  80  is symmetrical about its longitudinal axis, with  FIG.  14 C  showing a side cutaway view of the extractor along its longitudinal axis. The two forward edges  111  occupy a plane which passes near the approximate center of the longitudinal axis (dashed lines designated by M show this relationship in  FIG.  14 C ) of the pin receiving portion  99 . The lip  107  of the extractor  80  removably retains an ammunition cartridge in place within the cartridge recess  98 , against the face  92  of the bolt  21 . 
     Prior art extractors used with U.S. military M16/M4 type rifles and their derivatives, grasp approximately 22% or less of an ammunition cartridges rim. An extractor  80  according to the present invention grasps approximately 26% or more of an ammunition cartridge rim. In the preferred embodiment of the present design, the extractor claw  106  grabs approximately 17% more of an ammunition cartridge&#39;s rim as compared to the prior art M16/M4 type extractors. 
     The bore of the extractor&#39;s  80  pin receiving portion  99  is configured to align with the second bore  89  of the bolt  21  when the extractor  80  is positioned within the extractor recess  93 . A pivot pin  97  is extended through the second bore  89  of the bolt  21  and the pin receiving portion  99  of the extractor to pivotally engage the extractor  80  to the bolt  21 . The extractor  80  and thereby its claw  106  are rotatable between a first and second position (not shown). The first position has the lip  107  engaged with the rim of an ammunition cartridge. The second position has the extractor  80  pivotally biased such that the extractor claw  106  is being forced aside during the initial seating of an ammunition cartridge. 
     The extractor  80  as a unit is constructed to be received within the extractor recess  92  and the extractor gap  144  located on the cylindrical body  87  portion of the bolt  21 . The extractor recess  92  and extractor gap  144  are constructed to position the extractor  80  so that its forward end  108  coincides with the front end  82  of the bolt  21 . 
     The cartridge recess  98  is laterally defined by a round side wall  161 . The cartridge recess as a whole is defined by the round side wall  161  and the bolt face  92  (shown in  FIGS.  9 ,  15 A and  15 B ). The round side wall  161  is broken up by the extractor gap  144 . An ammunition cartridge resides within the cartridge recess  98  such that the case head of the cartridge rests against the face  92  of the bolt  21 . 
     The extractor mating surface  96  defines a portion of the circumference of the face  92  of the bolt  21 . In the preferred embodiment, the circumference of the bolt  21  face  92  is circular. In the preferred embodiment of the bolt  21 , the face  92  is in direct contact with the entire end portion, or case head, of a retained ammunition cartridge except for the portion which would be over the circumferential groove  162 . This method of manufacturing the extractor mating surface  96  and the face  92  does not require material which supports the bolt lugs  142  to be removed thereby compromising their structural integrity. 
     Referring to  FIGS.  10 - 13   , the extractor recess  93  is provided with a pair of spring wells  100 . The spring wells  100  are formed in the extractor recess  93  on opposite sides of the longitudinal bore  90  for the firing pin  29 . The central axis of each spring well  100  is approximately parallel to the other and is perpendicular to the longitudinal axis of the bolt  21 . The spring wells  100  are constructed to receive both a portion of the extractor spring  101  and the spring buffer  102 . The spring buffers  102  are manufactured from high temperature resistant VITON® fluoroelastomer, but other high temperature and solvent resistant materials may be used. The buffers  102  help keep the springs  101  in linear alignment with the spring wells  100 , prevent distortion of the springs  101 , and assist in preventing extractor bounce. 
     Extractor bounce is a phenomenon whereby the extractor slips off of a seated cartridges rim when the bolt comes under a heightened recoil force generated by the host firearm&#39;s discharge, resulting in a failure to extract. When the extractor  80  is engaged to the bolt  21  as previously described above, each one of the nipples  103  on the flange  104  engages a spring  101  while it is housed in a spring well  100 . In operation, the springs  101  place pressure on the flange  104  of the extractor  80 , thereby pivotally biasing the extractor  80  radially inward. This allows the claw  106  of the extractor to engage the rim of an ammunition cartridge. The springs  101  used for this purpose must also have sufficient flexibility to allow the extractor  80  to pivot radially outward during the recoil cycle so that the ammunition cartridge may be ejected. 
     As shown in  FIGS.  15 A and  15 B , seven integral bolt lugs  140 A,  140 B,  141 A,  141 B,  141 C,  141 D,  141 E (collectively referred to as “bolt lugs  142 ”) are located adjacent to the front end  82  of the bolt  21 . Each of the bolt lugs  142  is spaced evenly apart with the exception of lugs  140 A and  140 B. Each of the bolt lugs  142  radially extends about the longitudinal axis of the bolt  21 , adjacent the front end  82 . There is a gap  145  located between each pair of bolt lugs  142  with the exception of lugs  140 A and  140 B. Between lugs  140 A and  140 B there is defined a gap  144  for the extractor  80 . The extractor gap  144  is configured to receive the forward end  108  of the extractor  80  to include the extractor&#39;s claw  106  portion. 
     Each of the bolt lugs  142  defines a corresponding end wall  150 A,  150 B,  151 A,  151 B,  151 C,  151 D and  151 E (collectively referred to as “end walls  152 ”) and a pair of side walls  153 . At the junction where the side walls  153  meet with at least one of the end walls  152 , all sharp angles have been rounded and reinforced with radii removing potential stress risers and concentrators. 
     In the prior art, bolt lugs  140 A and  140 B had a portion of the material which would have supported them removed to accommodate the extractor  80  body, a process that is referred to as undercutting the bolt. Additionally, a portion of the bolt&#39;s face was removed in order to accommodate the forward end  108  and claw  106  portions of the extractor  80 . Structurally, undercutting the bolt constitutes removal of the material under the plane of sidewall  160 A of lug  140 A and the plane of the sidewall  160 B of the lug  140 B. This does not apply to the portion of the lugs  140 A and  140 B which protrudes above the face  92  of the bolt  21 . 
     The preferred embodiment of the bolt  21  as described herein does not rely on removing structural material which would otherwise strengthen the bolt  21 . Specifically, lugs  140 A and  140 B are not undercut by the extractor recess  93 . Further, the portion of the extractor gap  144  which accommodates the claw  106  portion of the extractor  80  is wider than the extractor&#39;s body  105  and the extractor recess  93 . The extractor recess  93  is defined as the relevant area and structural features as set forth above that are located below the horizontal plane defined by the face  92  of the bolt  21 . The extractor gap  144  is defined as the relevant opening located above the plane defined by the bolt face  92  and between lugs  140 A and  140 B of the bolt  21  (shown in  FIGS.  15 A and  15 B ). Lug  140 A may also be referred to as the first lug and lug  140 B may also be referred to as the second lug. 
     Best shown in  FIGS.  15 A,  15 B and  16    are the side walls which define the extractor gap  144  and extractor recess  93  of the bolt  21 . The extractor recess  93  and the extractor gap  144  interrupt the annular structure  163  about the front end  82  of the bolt  21  from which the lugs  142  radially extend. This annular structure  163  is defined as the material between the gaps  145  of the lugs  142  and the round side wall  161  of the cartridge recess  98 . At one end, the annular structure  163  terminates into two side walls  170 A and  171 A. Side wall  170 A is adjacent the extractor gap  144  while side wall  171 A is adjacent the extractor recess  93 . Side wall  170 A forms one side of the extractor gap  144  while side wall  171 A forms a portion of the side wall which is defined by the extractor recess  93 . 
     At its other end, the annular structure  163  terminates into two side walls  170 B and  171 B. Side wall  170 B is adjacent the extractor gap  144  while side wall  171 B is adjacent the extractor recess  93 . Side wall  170 B forms one side of the extractor gap  144  while side wall  171 B forms a portion of the side wall which is defined by the extractor recess  93 . 
     The side wall  171 A of the extractor recess is coplanar with the side wall  160 A of the first bolt lug  140 A. Both side walls  171 A and  160 A occupy the same plane which is indicated in  FIG.  15 B  by dashed line Y. Side wall  171 B is coplanar with the side wall  160 B of the second bolt lug  140 B. Both side walls  171 B and  160 B occupy the same plane which is indicated in  FIG.  15 B  by dashed line Z. As shown in  FIG.  15 B , the planes represented by the dashed lines Y and Z intersect. Side walls  171 A and  171 B assist in supporting the first bolt lug  140 A and the second bolt lug  140 B respectively 
     Side walls  170 A and  170 B occupy parallel planes. Further, side walls  170 A and  170 B define the width of the extractor gap  144  that is located above the face  92  of the bolt  21 . The extractor gap  144  is wider than the extractor recess  93  that is located below the face  92  of the bolt  21 . 
     Side wall  170 A lies on a plane which is indicated in  FIG.  15 B  by dashed line W. Side wall  170 B lies on a plane which is indicated in  FIG.  15 B  by dashed line X. Neither plane represented by X or W intersects with the other at any point. Further, the plane denoted by X intersects at the approximate junction of side wall  153  of bolt lug  141 B and the portion of the annular structure  163  adjacent thereto. The plane defined by W intersects at the approximate junction between the side wall  153  of bolt lug  141 D and the portion of the annular structure  163  adjacent thereto. 
     The bolt  21  of the present invention is turned, machined and precision ground from 9310 steel-alloy bar stock. The bolt  21  is then carburized for case hardness and tempered to increase core toughness. The bolt  21  is steel shot-peened by blasting selected surfaces with steel pellets to induce compressive stresses and improve fatigue life. A coating of nickel with TEFLON®, polytetrafluoroethylene a fluoropolymer, is applied to the bolt  21  to reduce the friction coefficient between the bolt  21  and the bolt carrier  20 , and the bolt  21  and the barrel extension (not shown) of the barrel  12 . 
     The bolt carrier  20  is machined from an 8620 steel alloy and carburized or case hardened for wear resistance. A coating comprised of nickel and TEFLON®, polytetrafluoroethylene a fluoropolymer, is applied to the bolt carrier  20 . Electroless Nickel provides wear resistance for the bolt carrier  20  and makes the part easier to clean as carbon and other fouling resulting from the use of the host firearm is easier to remove. The coating also provides the parts with a natural lubricity. Even with the specificity provided above, it should be understood that the entire bolt carrier  20  and bolt  21  of the present invention could be made of conventional materials, preferably hard structural material such as steel or stainless steel and coated with prior art surface finishes such as an electrochemical phosphate conversion coating. 
     The bolt  21  and bolt carrier  20  of the present invention may be used in conjunction with each other or independently with prior art AR15/M4 bolt carriers or bolts. The method of securing the bolt  21  to the bolt carrier  20  is substantially similar to the methods used in the prior art. Initially the springs  101  and their buffers  102  are inserted into the spring wells  100  located within the extractor recess  93  of the bolt  21 . The extractor  80  is placed within the recess  93  so that the two nipples  103  located on its flange  104  are in direct contact with the springs  101 . With the pin receiving portion  99  of the extractor  80  aligned with the second bore  89  of the bolt  21 , a pivot pin  97  is inserted therethrough to secure the extractor  80  to the bolt  21 . 
     The ejector  120  and spring  122  are received within a bore  121  present on the cylindrical body  87  of the bolt  21 , and retained in place through the use of a roll pin  123  as is common throughout the prior art. The roll pin  123  is received in a bore  124  present near the front end  82  of the bolt  21 . The gas rings  85  are flexed so that they may be received within the groove  84  present near the rear end  81  of the bolt  21 . After the bolt  21  and bolt carrier  20  are assembled as described above, the bolt  21  is inserted into an opening  24  found on the carriers  20  forward end. The first bore  88  of the bolt  21  is oriented so that it aligns with the cam slot  26  of the bolt carrier  20 . The cam pin  27  is then inserted through the cam slot  26  and into the first bore  88  of the bolt  21  and rotated so that an opening present along its bottom side is aligned with the bore  39  of the bolt carrier  20 , the specifics of which are well known in the prior art. Next the firing pin  29  is inserted through the bore  30  of the bolt carrier  20  and into the longitudinal bore  90  of the bolt  21 . The firing pin  29  is secured in placed through the use of a cotter pin  40 . The cotter pin  40  is inserted into an opening  41  located on the bolt carrier&#39;s exterior and oriented within the opening  41  as described above. 
     Thus the assembly of the bolt  21  and bolt carrier  20  has been described. By reversing the steps detailed above the bolt carrier  20  and bolt  21  may be disassembled for maintenance and repaired as required. 
     In sum, the present invention provides an improved means for securing a gas nozzle to the bolt carrier of an M16 type rifle. By integrating the gas key  30  onto the bolt carrier  20 , the problems associated with the prior art attachment methods are eliminated. By threadedly securing the extension nozzle  50  to the gas key  30  and retaining the extension nozzle  50  in place through the use of a roll pin  31 , a superior attachment method is provided. This method of manufacturing a bolt carrier eliminates the extraction and ammunition feeding problems associated with gas leakage linked to the compromised union between the prior art gas key  61  and bolt carrier  60 . 
     The present invention also provides an improved structure on the bolt carrier  20  which orients the cotter pin  40  in a position that optimizes its service life. The opening  41  for the cotter pin  40  holds it in a vertical orientation which places its widest profile towards the back side of the annular flange  44  of firing pin  29 . The use of this feature is not limited to rifles using the direct gas operating system seen on the rifle  300  shown in  FIG.  6   ; it is also applicable and appropriate for use with indirect gas operated rifles, commonly referred to as piston operated rifles. 
     Additionally, there is provided a bolt  21  which provides an extractor recess  93  which does not rely on undercutting the face  92  of the bolt  21  in order to accommodate an extractor  80 . Also provided is an extractor which has been designed to grasp at least 26% of an ammunition cartridge&#39;s rim. 
     In an alternate embodiment the extractor flange  104  could be modified to use a prior art spring and buffer without departing from the significant advantages offered by the herein disclosed apparatus. 
     In still another alternate embodiment, the bolt face  92  could be machined without the inclusion of the circumferential groove  162 . 
     In yet another alternate embodiment of the bolt, the features of the present invention have been adapted to work with ammunition types used with AR15/M16 type rifles, and their unique bolts, that are not based around the military standard 5.56×45 mm ammunition cartridge. This alternative embodiment of the bolt, generally designated by reference numeral  200 , is shown in  FIGS.  17 - 24   . 
     The preferred embodiment of the bolt  21  shown in  FIG.  1    is configured to work optimally with the ammunition casing used with 5.56×45 mm ammunition and all structural and dimensional equivalents. Examples of ammunition which use a structurally equivalent ammunition casing for the purposes of this disclosure are .223 Remington, .300 Whisper and .300 BLK, to name a few. The critical case dimension is the portion of the ammunition cartridge, or case head, which resides within the cartridge recess on the bolts front end. Ammunition cartridges which have larger case heads (also referred to as alternative cartridges herein), such as 6.8 mm SPC and 7.62×39 mm, typically require the bolt face to have a larger opening. Prior art bolt designs for the 6.8 mm SPC cartridge and other alternative cartridges, rely on removing an approximately rectangular portion of the bolts face and adjacent lugs along with a portion of the annular structure to which the bolt lugs are attached in order to accommodate the cartridges case head and the extractor (see  FIG.  25 B ). Further, material is removed from the extractor claw portion, with the extractor&#39;s lip being reduced in size due to the diameter of the alternative ammunition cartridge&#39;s case head. These modifications to the extractor are required so that the extractor can accommodate the alternative cartridges case head and still allow the extractor to seat properly against the mating surface provided on the bolt. 
     Manufacturing a bolt for use with AR15/M4/M16 type rifles which can accommodate the cartridge case head of these alternative cartridges results in structural material located below the face of the bolt, that is located behind the bolt lugs adjacent the extractor gap to be removed, thus compromising their structural integrity. The reduction in the size of the extractor claw reduces its contact surface area, thereby reducing the extractor&#39;s ability to effectively remove spent ammunition cartridges during the firing and extraction cycle of the host firearm. Therefore there exist a need to overcome these and other deficiencies in the prior art. 
     Except as specified herein, this alternate embodiment bolt  200  is substantially the same as the bolt  21  shown in  FIG.  1   . The bolt  200  is comprised of an elongated body having a rear end  201  and a front end  202  located along a longitudinal axis. Located about the rear end  201  of the bolt  200  are two circumferential flanges  203  which occupy parallel plains leaving a space, or groove  204 , therebetween ( FIG.  18   ). The groove  204  is formed to accept a series of gas sealing rings  205  ( FIG.  18   ). The bolt  200  is formed with a neck portion  206  extending between the annular flanges  203  and the cylindrical body  207  ( FIG.  18   ). The cylindrical body  207  of the bolt defines a first bore  208  and a second bore  209  ( FIG.  17   ), both of which extend through the cylindrical body  207  of the bolt  200 . In the interior of the bolt  200 , there is formed a longitudinal bore  210  ( FIG.  17   ) which receives a firing pin. The cylindrical body  207  also defines an exterior surface  211  thereabout. The face portion  223  of the bolt  200  serves as a cartridge bearing surface and is located near the front end  202  ( FIGS.  17  and  23 A- 23 B ). A separate structure but integral feature of the face portion  223  is the circumferential groove  232  present on the exterior portion of what defines the bolt face  223  (shown in  FIGS.  23 A and  23 B ). The circumferential grove  232  is present to facilitate the accumulation of debris incidental to the firing of the associated indirect gas operated rifle  300  (see  FIG.  6   ). In addition, the circumferential groove  232  about the bolt  200  face  223  relieves material stress. When manufacturing the bolt for use with alternative cartridges, the diameter of the bolt&#39;s face  223  is increased resulting in a portion of the bolt face  223  being removed, creating a gap  236  thereon ( FIGS.  23 A- 23 B and  24   ). This gap  236  is required as it provides necessary clearance for the extractor  240  disclosed herein. 
     The cylindrical body  207  portion of the bolt  200  defines an extractor recess  212  ( FIG.  18   ). The extractor recess  212 , formed on the exterior surface  211  ( FIGS.  17  and  24   ), is in communication with the longitudinal bore  210  ( FIG.  20   ), or firing pin bore. A bearing portion  213  ( FIGS.  18  and  20   ) for the extractor  240  resides within the extractor recess  212  and is integrally formed with the body  207  of the bolt  200 . The extractor recess  212  also includes a mating surface  214  (see  FIGS.  18 ,  20  and  21   ) defining a curved side wall  237  ( FIG.  23 B ) substantially parallel to the exterior surface  211  of the bolt  200  ( FIGS.  18 ,  20  and  21   ). In order to form the mating surface  214  for the extractor  240 , a segment of the bolt face  223  and the underlying material is removed (see  FIGS.  23 A and  23 B ), leaving a gap  236 . The underside  241  ( FIGS.  22 C- 22 D ) of the extractor  240  is also curved so that it may engage with and rest against the mating surface  214 . 
     The extractor is shown in  FIGS.  22 A- 22 D . The rearward end of the extractor  240  defines a flange  246  which serves as a bearing surface for the extractor springs  243  (see  FIGS.  18 - 20   ). Located on the flange  246  are two nipples  245  ( FIGS.  22 C and  22 D ) each of which individually engage with a portion of an extractor spring  243  ( FIGS.  18 - 19   ). 
     The extractor body  247  extends between the flange  246  and the extractor claw  248 , located on the extractor&#39;s forward end  250  ( FIG.  22 A ). The extractor body  247  defines a pin receiving portion  242  along its length. The pin receiving portion  242  is a bore that runs perpendicular to the longitudinal axis of the extractor  240 . The extractor claw  248  defines a recess  251  having an upper portion or lip  249  ( FIGS.  22 C- 22 D ). The lip  249  portion of the extractor claw  248  is constructed to engage with the rim of an ammunition cartridge. Structurally, the extractor claw  248  portion of the extractor  240  is wider than the extractor body  247 . Further, the circumferential edge  252  ( FIG.  22 C ) on the interior of the lip  249  comes to two forward edges  253  ( FIG.  22 D ) which are located on opposite sides of the extractor claw  248 . The extractor  240  is symmetrical about its longitudinal axis, with  FIG.  22 C  showing a side cutaway view of the extractor along its longitudinal axis. The two forward edges  253  occupy a plane which intersects with, and bisects, the nipple  245  located on the extractor&#39;s  240  flange  246  (dashed lines designated by “D” show this relationship in  FIG.  22 C ). The lip  249  of the extractor  240  removably retains an ammunition cartridge in place within the cartridge recess  215  (see  FIG.  17   ), against the face  223  of the bolt  200 . 
     An extractor  240  according to the present alternate embodiment of the invention grasps approximately 0.0077 square inches of a 6.8 mm SPC ammunition cartridge rim which is approximately 57% more of the ammunition cartridges rim as compared to some of the prior art M16/M4 type extractors used with 6.8 mm SPC bolts. 
     The bore of the extractors  240  pin receiving portion  242  ( FIGS.  22 C- 22 D ) is configured to align with the second bore  209  ( FIG.  17   ) of the bolt  200  when the extractor  240  is positioned within the extractor recess  212 . A pivot pin  254  ( FIG.  18   ) is extended through the second bore  209  of the bolt  200  and the pin receiving portion  242  of the extractor to pivotally engage the extractor  240  to the bolt  200 . The extractor  240  and thereby its claw  248  are rotatable between a first and second position (not shown). The first position has the lip  249  engaged with the rim of an ammunition cartridge. The second position has the extractor  240  pivotally biased such that the extractor claw  248  is being forced aside during the initial seating of an ammunition cartridge. 
     The extractor  240  as a unit is constructed to be received within the extractor recess  212  and the extractor gap  222  ( FIGS.  23 A- 23 B ) located on the cylindrical body  207  portion of the bolt  200 . The extractor recess  212  and extractor gap  222  are constructed to position the extractor  240  so that its forward end  250  coincides with the front end  202  of the bolt  200 . 
     The cartridge recess  215  is laterally defined by an approximately round side wall  231 . The cartridge recess as a whole is defined by the round side wall  231 , the bolt face  223 , and the gap  236  (shown in  FIGS.  17 ,  23 A and  23 B ). The round side wall  231  is broken up by the extractor gap  222 . An ammunition cartridge resides within the cartridge recess  215  such that the case head of the cartridge rests against the face  223  of the bolt  200 . The gap  236  results in a portion of the ammunition cartridges rim not being in contact with the bolt face  223 . 
     In one embodiment of the bolt  200 , the face  223  is in direct contact with the entire end portion, or case head, of a retained ammunition cartridge except for the portion that is located over the circumferential groove  232  or the gap  236  formed thereon. This method of manufacturing the extractor mating surface  214  and the face  223  does not require material which supports the bolt lugs  218 A and  218 B ( FIGS.  17 - 18   ) to be removed, thereby compromising their structural integrity. 
     Referring to  FIGS.  18 - 21  and  24   , the extractor recess  212  is provided with a pair of spring wells, springs  243  and spring buffers constructed substantially the same as those disclosed in connection with the bolt  21 . These components are assembled onto the bolt  200  and work in conjunction with the extractor  240  to perform the same function described in connection with the bolt  21  and extractor  80 . Further, the provided combination of components (spring wells, springs and spring buffers) provide the same benefits for all disclosed embodiments of the bolt described herein where such components are incorporated. In particular, the combination of the spring wells, springs and spring buffers assist in eliminating extractor bounce, a phenomenon whereby the extractor slips off of a seated cartridges rim when the bolt comes under a heightened recoil force generated by the host firearms discharge, resulting in a failure to extract. 
     As shown in  FIGS.  23 A and  23 B , seven integral bolt lugs  218 A,  218 B,  219 A,  219 B,  219 C,  219 D,  219 E (collectively referred to as “bolt lugs  220 ”) are located adjacent to the front end  202  of the bolt  200 . Each of the bolt lugs  220  is spaced evenly apart with the exception of lugs  218 A and  218 B. Each of the bolt lugs  220  radially extends about the longitudinal axis of the bolt  200 , adjacent the front end  202 . There is a gap  224  located between each pair of bolt lugs  220  with the exception of lugs  218 A and  218 B. Between lugs  218 A and  218 B there is defined a gap  222  for the extractor  240 . The extractor gap  222  is configured to receive the forward end  250  of the extractor  240  to include the extractors claw  248  portion. 
     Each of the bolt lugs  220  defines a corresponding end wall  225 A,  225 B,  226 A,  226 B,  226 C,  226 D and  226 E (collectively referred to as “end walls  227 ”) and a pair of side walls  228 , except for lugs  225 A and  225 B. At the junction where the side walls  228  meet with at least one of the end walls  227 , all sharp angles have been rounded and reinforced with radii removing potential stress risers and concentrators. 
     In the prior art, bolt lugs  284 A and  284 B have a portion of the material which would have supported them removed to accommodate the extractor body. Additionally, a portion of the bolts face is removed in order to accommodate the claw portion and a portion of the body of the extractor (see  FIG.  25 B ). Removing a portion of the prior art bolt  280  face creates a gap  285  which is defined by one long straight side wall  281  with two shorter side walls,  282 A and  282 B. Sides walls  282 A and  282 B are located at opposite ends of side wall  281 , both side walls  282 A and  282 B are at a 90 degree angle relative to side wall  281 . This method of constructing the bolt  280  results in the gap  285  having generally rectangular shape and in the removal of structural material located directly behind the lugs (see  FIG.  25 B ). The removal of material located behind bolt lugs  283 A and  284 B and below the horizontal plane defined by the bolt face, thereby creating a gap to accommodate the extractor is referred to as undercutting the bolt. 
     Referring back to  FIGS.  23 A and  23 B , structurally, undercutting the bolt lugs  220  constitutes removal of material to the left of plane G of the sidewall  229 A of lug  218 A and to the right of plane H of the sidewall  229 B of lug  218 B for the purpose of including the extractor recess  212 . This does not apply to the annular structure  233  located behind lugs  218 A and  218 B which protrudes above the face  223  of the bolt  200 . The bolt  200  as described herein does not rely on removing structural material which would otherwise strengthen the bolt lugs  220  simply to accommodate the extractor  240 . Specifically, lugs  218 A and  218 B are not undercut by the extractor recess  212  or the resulting gap  236  in the bolt face  223 . Further, the portion of the extractor gap  222  which accommodates the claw  248  of the extractor  240  is wider than the extractor body  247  and the extractor recess  212 . The extractor recess  212  is defined as the relevant area and structural features as set forth above that are located below the horizontal plane defined by the face  223  of the bolt  200 . The extractor gap  222  is defined as the relevant opening located above the horizontal plane defined by the bolt face  223 , located between lugs  218 A and  218 B of the bolt  200  (shown in  FIGS.  23 A and  23 B ). Lug  218 A may also be referred to as the first lug and lug  218 B may also be referred to as the second lug. 
     Best shown in  FIGS.  23 A,  23 B and  24    are the side walls which define the extractor gap  222  and extractor recess  212  of the bolt  200 . The extractor recess  212  and the extractor gap  222  interrupt the annular structure  233  ( FIG.  23 B ) about the front end  202  of the bolt  200  from which the lugs  220  radially extend. This annular structure  233  is defined as the material between the gaps  224  of the lugs  220  and the interior side wall  231  of the cartridge recess  215 , including the material of the bolt directly behind the lugs  220 . At one end, the annular structure  233  terminates into two side walls  234 A and  235 A ( FIG.  23 B ). The length of side wall  234 A extends from the top of bolt lug  218 A, adjacent the front end  202  of the bolt, to the horizontal plane defined by the bolt face  223 . As a result, side wall  234 A defines a portion of the extractor gap  222 . Side wall  235 A defines a portion of, and is adjacent to, the extractor recess  212  and the gap  236  present in the bolt face  223 . 
     At its other end, the annular structure  233  terminates into two side walls,  234 B and  235 B ( FIG.  23 B ). The length of side wall  234 B extends from the top of the bolt lug  218 B, adjacent the front end  202  of the bolt, to the horizontal plane defined by the bolt face  223 . As a result, side wall  234 B defines a portion of the extractor gap  222  in conjunction with side wall  234 A. Side wall  235 B defines a portion of, and is adjacent to, the extractor recess  212  and the gap  236  present in the bolt face  223 . The gap  236  in the bolt face  223  is generally defined by a portion of both side wall  235 A and  235 B, located at opposite ends of a convex shaped side wall  237  extending therebetween (see  FIG.  23 B ). This gap  236  is the result of the removal of a portion of the circumferential groove  232  which is part of the bolt face  223  as a whole. 
     The side wall  235 A of the extractor recess is coplanar with the side wall  229 A of the first bolt lug  218 A. Both side walls  235 A and  229 A occupy a same plane which is indicated in  FIG.  23 A  by dashed line G. Side wall  235 B is coplanar with the side wall  229 B of the second bolt lug  218 B. Both side walls  229 B and  235 B occupy a same plane which is indicated in  FIG.  23 A  by dashed line H. As shown in  FIG.  23 A  the planes represented by the dashed lines G and H intersect. Side walls  235 A and  235 B ( FIG.  23 B ) assist in supporting the first bolt lug  218 A and the second bolt lug  218 B respectively. 
     Side walls  234 A and  234 B occupy parallel planes ( FIG.  23 B ). Further, side walls  234 A and  234 B define the width of the extractor gap. The extractor gap  222  is wider than the extractor recess  212  that is located below the horizontal plane defined by the face  223  of the bolt  200 . 
     Side wall  234 A lies on a plane which is indicated in  FIG.  23 A  by dashed line E. Side wall  234 B lies on a plane which is indicated in  FIG.  23 B  by dashed line F. Neither plane represented by E or F intersects with the other at any point. Further, the plane denoted by dashed line F crosses the annular structure  233  at the junction of side wall  228  and bolt lug  219 B. The plane defined by dashed lined E crosses the annular structure  233  of the bolt  200  at the junction of side wall  228  and bolt lug  219 D. 
     The ejector  260  and spring  262  ( FIGS.  18 - 19   ) are received within a bore  261  ( FIG.  21   ) present on the cylindrical body  207  of the bolt  200 , and retained in place through the use of a roll pin  263  ( FIGS.  18 - 19   ) as is common throughout the prior art. The roll pin  263  is received in a bore  264  ( FIG.  21   ) present near the front end  202  of the bolt  200 . The gas rings  205  are flexed so that they may be received within the groove  204  ( FIGS.  18 - 19   ) present near the rear end  201  of the bolt  200 . Alternatively, the gas rings may be omitted, as appropriate, with some variants of the AR15/M16/M4 family of firearms. 
     The bolt  200  used with alternative cartridges, 6.8SPC specifically for the embodiment illustrated, is manufactured in the same manner as the embodiment of the bolt  21  shown in  FIG.  1   . Any differences between the two bolt designs  21  and  200  are structural in nature and defined herein and/or illustrated in the associated drawings. Specifically, the manufacture of the bolt  200  to include the gap  236  is useful and required for optimal function of the bolt  200  when used with alternative cartridges, such as 6.8 mm SPC. 
     Bolt  200  is capable without modification of working with the bolt carrier  20  described herein or with the various other bolt carriers found in the prior art which are adaptable for use with AR15/M16/M4 type rifles, to include those which rely on either a gas tube or a gas piston. 
     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 disclosed embodiments. 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.