Patent Publication Number: US-7594464-B2

Title: Sound suppressors for firearms

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Application No. 60/788,915, filed Apr. 3, 2006, which application is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   This invention relates to sound suppressor apparatus for firearms, and more particularly to a sound suppressor having a back section configured in relation to a muzzle fixture of a firearm for improving sound suppression. 
   Sound suppressors for firearms conventionally include a generally cylindrical sound suppressor body including a sound suppressing front section and a back section adapted to be secured to the firearm. The back section may be directly secured to the firearm muzzle, or it may be secured to a muzzle fixture (such as a flash suppressor, muzzle brake, compensator or adapter) which is secured to the firearm&#39;s muzzle. 
   Sound suppressors are known in the art that include a back section having one or two chambers for receiving combustion gases exiting from the firearm&#39;s muzzle upon the firing of the firearm and for applying those gases to the sound suppressor&#39;s front end. For example, a dual chamber back section is shown in combination with a muzzle fixture such as a flash suppressor in U.S. Pat. No. 6,948,415 to John W. Matthews et al., assigned to the assignee of the present application, while a dual chamber back section is shown (without provision of a flash suppressor or other muzzle fixture) in U.S. Pat. No. 4,907,488 to Oswald P. Seberger. 
   There nevertheless exists a need for firearm sound suppressors with improved overall sound suppressor performance, which need is fulfilled by the back section configuration of sound suppressors in accordance with the present invention. 
   SUMMARY OF THE INVENTION 
   The present invention provides a sound suppressor having a back section configured with at least three interrelated chambers in association with a muzzle fixture, for significantly improving overall sound suppressor performance. According to one aspect of the present invention, there is provided a sound suppressor apparatus for a firearm having a barrel extending along a longitudinal axis, comprising: a muzzle fixture for the firearm, the muzzle fixture including an axial passageway and a lateral vent; and a sound suppressor body including a sound suppressing front section and a back section, the back section adapted to coaxially receive the muzzle fixture, the back section configured with at least three interrelated chambers when the muzzle fixture is received by the back section for effecting energy attenuation of at least a portion of combustion gases exiting the muzzle fixture from a firing of the firearm when the muzzle fixture is secured to the barrel. 
   In its preferred embodiment, the sound suppressor apparatus for a firearm having a barrel extending along a longitudinal axis, comprises: a muzzle fixture for the firearm, the muzzle fixture including an axial passageway and a lateral vent; and a sound suppressor body including a sound suppressing front section and a back section, the back section adapted to coaxially receive the muzzle fixture, the back section including a forward chamber communicating with the front section and situated generally forwardly of the muzzle fixture when the muzzle fixture is received by the back section, a first lateral chamber communicating with the vent when the muzzle fixture is received by the back section, and a second lateral chamber, the second lateral chamber and the forward chamber communicating with each other. The first lateral chamber is situated about the muzzle fixture when the muzzle fixture is received by the back section, and the second lateral chamber is situated about the first lateral chamber. 
   In the preferred embodiment, the muzzle fixture includes a forward portion which includes the vent; the forward chamber includes a forward facing annular wall about an opening to the axial passageway of the muzzle fixture when the muzzle fixture is received by the back section; the lateral chamber circumferentially surrounds the front portion of the muzzle fixture when the muzzle fixture is received by the back section; and the second lateral chamber circumferentially surrounds the first lateral chamber. The back chamber preferably includes ports about the annular wall of the forward chamber for enabling the second lateral chamber and the forward chamber to communicate with each other. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed to be characteristic of the present invention, together with advantages thereof, will be understood from the following description considered in connection with the accompanying drawings in which a preferred embodiment of the 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 as a definition of the limits of the invention. 
       FIG. 1  is a side view of a firearm equipped with a muzzle fixture, specifically a flash suppressor, which may be used in combination with a preferred embodiment of a sound suppressor according to the present invention; 
       FIG. 2  is a side view of the flash suppressor shown in  FIG. 1 ; 
       FIG. 3  is a cross-sectional view of the flash suppressor of  FIG. 2 , taken along the line  3 - 3  of  FIG. 2  and viewed in the direction of the appended arrows; 
       FIG. 4  is a longitudinal cross-sectional view of the flash suppressor of  FIG. 2 ; 
       FIG. 5  is a longitudinal cross-sectional view of a preferred embodiment of a sound suppressor assembly according to the present invention, including the flash suppressor shown in  FIGS. 2-4 ; 
       FIG. 6  is a side elevation view of a preferred embodiment of the sound suppressor&#39;s back section component shown in  FIG. 5 ; 
       FIG. 7  is a front end view of the back section component of  FIG. 6 ; and 
       FIG. 8  is a longitudinal cross-sectional view of the back section component of  FIGS. 6 and 7 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Turning to the drawings, there is illustrated in  FIG. 1  an example of a firearm  20 , such as an M-4 or M-16 automatic rifle, to which a firearm accessory, in particular a sound suppressor according to the present invention, may be removably secured. The firearm  20  includes a barrel  22  having a longitudinal axis a along which a fired bullet is caused to travel. The firearm&#39;s muzzle is equipped with a flash suppressor  24  (although another type of muzzle fixture may be employed, such as a muzzle brake, compensator or adapter) having a forward opening  26  through which the fired bullet exits. The flash suppressor  24  or other muzzle fixture may be fixedly secured to the firearm barrel  22  such as by welding or other conventional securement means (for example, by means of mating threads externally about the barrel muzzle and internally of the flash suppressor together with a high-temperature cement or a locking device for preventing rotation of the installed flash suppressor  24  with respect to the firearm barrel  22 ), or the muzzle end portion of the firearm barrel  22  may be machined in the configuration of the flash suppressor  24 . 
   As used herein, the word “front” or “forward” corresponds to the firing direction of the firearm  20  (i.e., to the right as shown in  FIGS. 1 ,  2 ,  4 ,  5 ,  6  and  8 ); “rear” or “rearward” corresponds to the direction opposite the front or forward direction; and “longitudinal” means the direction along or parallel to the longitudinal axis a of the barrel  22  of the firearm  20 , or to the longitudinal axis a′ of the sound suppressor assembly  38 . 
   As shown in  FIGS. 2-4 , an example of the flash suppressor  24  includes a generally cylindrical wall  28  with a forward portion  36  including an axial passageway  30  and a vent  34  through the wall  28  of the flash suppressor&#39;s forward portion  36 , although it may be appreciated that other vented muzzle fixtures may be used as well. The axial passageway  30  is forwardly of and communicates with a threaded bore  32  for threadedly securing the flash suppressor  24  to the threaded muzzle end of the firearm barrel  22 . The lateral vent  34  is preferably symmetrically distributed through the forward portion  36  and typically comprises at least one slot through the wall  28 , longitudinally extending along and circumferentially evenly spaced about a sector of the forward portion  36  of the flash suppressor  24 . In the example of the flash suppressor  24  shown in  FIGS. 2-4 , the longitudinally extending lateral slots are five in quantity (referred to individually as slots  34   a ,  34   b ,  34   c ,  34   d  and  34   e , and referred to collectively as the vent  34  or slots  34 ), and are rotationally spaced about an approximately 180° sector of the forward portion  36 . Proper installation of the flash suppressor  24  to the muzzle end of the firearm barrel  22  would require that the middle slot  34   c  (i.e., the third slot in this five-slot vent  34 ) be at the twelve o&#39;clock or top dead center position of the barrel  22 . Techniques for such installation of the flash suppressor  24  (as well as other vented muzzle fixtures) are discussed in U.S. patent application Ser. No. 11/015,685, filed Dec. 16, 2004, of Brooke C. Smith, assigned to the assignee of the present application and incorporated in full herein by reference. 
   The preferred embodiment of a sound suppressor assembly  38  of the present invention, represented in  FIG. 5 , comprises a generally cylindrical sound suppressor body  40  having a longitudinal axis a′, removably secured to the flash suppressor  24 . For example, a retaining ring  42  cooperatively engages a ridge  43  near the rear end of the flash suppressor  24  and a rear collar  44  of the sound suppressor body  40 , such as taught in U.S. Pat. No. 6,948,415 to John W. Matthews et al. and assigned to the assignee of the present application, and in U.S. patent application Ser. No. 11/171,178 filed Jun. 29, 2005, of Barry W. Dueck et al. and assigned to the assignee of the present application. U.S. Pat. No. 6,948,415 and application Ser. No. 11/171,178 are incorporated in full herein by reference. 
   The sound suppressor body  40  comprises a back section  46  including a back section component  48  (see also  FIGS. 6-8 ) having a longitudinal bore  50  for coaxially receiving the flash suppressor  24 . The sound suppressor body  40  further includes a main sound suppressing front section  52  fixedly secured to the back section  46  (for example, by welding along their circumferences as at  54 ) and having an axial exit opening  56  through which a fired bullet exits when the sound suppressor body  40  is secured to the flash suppressor  24  which itself is secured to the firearm barrel  22 , with the longitudinal axes a and a′ coinciding. Sound suppressor front sections are well known in the sound suppressor art, typically including a series of baffles (represented by the baffles  58  in  FIG. 5 ) forwardly of a first or “blast” baffle  59 , successively deflecting combustion gases resulting from the firearm&#39;s firing of a bullet and for thereby muffling the sound consequent thereto. Sound suppressors including baffled front sections are disclosed, for example, in U.S. Pat. Nos. 4,576,083 and 4,907,488, to Oswald P. Seberger, incorporated in full herein by reference. 
   The present invention provides a back section  46  which increases the overall sound suppressing performance of a sound suppressor by decreasing the work required by the main sound suppressing front section  52 . This is accomplished by configuring the sound suppressor&#39;s back section  46  in relation to the flash suppressor  24  such that at least three interrelated chambers are formed in the back section for preprocessing portions of the combustion gases before introducing such portions to the sound suppressor&#39;s front section. 
   Specifically, a portion of the bore  50  of the back section component  48  is of increased diameter so that, when the flash suppressor  24  is received by the back section component bore  50  and the sound suppressor body back section  46  is removably secured to the flash suppressor  24  as previously described and shown in  FIG. 5 , the increased diameter bore portion  60  of the back section component  48  circumferentially surrounds the forward portion  36  of the flash suppressor  24 , forming a first lateral chamber  62  about the flash suppressor&#39;s forward portion  36  and communicating with the flash suppressor&#39;s vent slots  34 . 
   The outer surface of the back section component  48  includes a recess  64  between a rear annular flange  65  and the tubular front side wall  72 , the recess  64  forming a second lateral chamber  66  with the tubular housing  68  fixedly secured to the back section component  48 . 
   The sound suppressor back section  46  further includes a forward chamber  70  situated generally forwardly of the installed flash suppressor  24 . The forward chamber  70  is defined by the tubular front side wall  72  of the back section component  48 , a forward facing annular wall  74  inwardly extending from the tubular front side wall  72 , and the rear surface  76  of the blast baffle  59 . The forward chamber  70  is open to the axial passageway  30  of the flash suppressor  24  at the flash suppressor&#39;s forward opening  26 , which may extend into the forward chamber  70 , and the forward chamber  70  communicates with the sound suppressor&#39;s front section  52  through a central aperture  78  through the blast baffle  76 . The forward chamber  70  and the second lateral chamber  66  communicate with each other, such as through a series of ports  80  extending through the tubular front wall  72  about the annular wall  74  of the forward chamber  70  and into the second lateral chamber  66 . 
   Upon firing of a bullet by the firearm  20  to which the sound suppressor assembly  36  is secured with the longitudinal axis a′ coinciding with the longitudinal axis a, the bullet proceeds axially through the flash suppressor passageway  30 , the forward chamber  70 , the blast baffle central aperture  78  and axial openings through the sound suppressor front section  52 , finally exiting through the axial exit opening  56  at the sound suppressor&#39;s front end. 
   Although the sound suppression mechanism of the three interrelated chambers of the preferred embodiment of the present invention is not completely understood, it is believed that the firearm&#39;s combustion gases incident to the bullet&#39;s firing, which follow the bullet through the barrel  22 , proceed through the flash suppressor&#39;s axial passageway  30  and into the back section&#39;s forward chamber  70  while a portion of those gases are diverted through the flash suppressor&#39;s vent slots  34  into the first lateral chamber  62 . The gases filling the first lateral chamber  62  proceed back through the flash suppressor&#39;s vent slots  34  to mix with the gases in the forward chamber  70 . The fired bullet&#39;s momentary blocking of the blast baffle&#39;s axial aperture  78  enables much of the gases in the forward chamber  70  to be deflected by the rearward surface  76  of the blast baffle  59 , by the forward chamber&#39;s tubular side wall  72  and by the forward facing annular wall  74 . A portion of the deflected gases enters the second lateral chamber  66  through the forward chamber&#39;s side ports  80 , and gases from the filled second lateral chamber  66  reenter the forward chamber  70  through the side ports  80 . Such rebounding of the gases and their interaction among the three chambers of the back section  46  continues with consequent energy attenuation, and with the gases including the energy attenuated gases proceeding through the blast baffle aperture  78  and into the sound suppressor&#39;s front section  52  to interact with the baffles  58  with resulting overall sound suppression efficiency. 
   Thus, there has been described a preferred embodiment of a firearm sound suppressor having a back section configured in relation to the firearm&#39;s muzzle fixture such that at least three interrelated chambers are formed in the back section for preprocessing portions of the combustion gases before such portions are processed by the sound suppressor&#39;s front section. Other embodiments of the present invention, and variations of the embodiment described herein, may be developed without departing from the essential characteristics thereof. Accordingly, the invention should be limited only by the scope of the claims listed below.