Patent Publication Number: US-8973481-B2

Title: Firearm sound suppressor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 13/348,811 filed Jan. 12, 2012 which is hereby incorporated by reference in its entirety. 
     This application is a continuation-in-part of U.S. patent application Ser. No. 13/348,834 filed Jan. 12, 2012 which is hereby incorporated by reference in its entirety. 
     This application is a continuation-in-part of U.S. patent application Ser. No. 29/420,120 filed May 4, 2012 which is hereby incorporated by reference in its entirety. 
     This application is a continuation-in-part of U.S. patent application Ser. No. 13/281,350 filed Oct. 25, 2011, which is a continuation-in-part of U.S. patent application Ser. No. 12/482,664 filed Jun. 11, 2009, all of which are hereby incorporated by reference in their entireties. 
     U.S. patent application Ser. No. 13/281,350 is a continuation-in-part of U.S. patent application Ser. No. 13/102,819 filed May 6, 2011, which is a continuation of U.S. patent application Ser. No. 12/582,958 filed Oct. 21, 2009, which is a continuation of U.S. patent application Ser. No. 11/171,178 filed Jun. 29, 2005, which is a continuation-in-part of U.S. patent application Ser. No. 10/703,971 filed Nov. 6, 2003, all of which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     This disclosure relates to firearms in general, and more particularly, to sound (e.g., noise) suppressors for firearms. 
     2. Related Art 
     Firearms, such as pistols or rifles, utilize expanding high-pressure gases generated by a burning propellant to expel a projectile from the weapon at a relatively high velocity. When the projectile, or bullet, exits the muzzle end of the weapon&#39;s barrel, a bright, “muzzle flash” of light and a high-pressure pulse of combustion gases accompany it. The rapid pressurization and subsequent depressurization caused by the high-pressure pulse gives rise to a loud sound known as “muzzle blast,” which, like muzzle flash, can readily indicate to a remote enemy both the location of the weapon and the direction from which it is being fired. In some situations, such as covert military operations, it is highly desirable to conceal this information from the enemy by suppressing the flash and/or eliminating or substantially reducing the amplitude of the muzzle blast. 
     The use of sound suppressors (e.g., also referred to as noise suppressors and silencers) on firearms to reduce the amplitude of their muzzle blasts is known. Suppressors operate to reduce muzzle blast by reducing and controlling the energy level of the propellant gases accompanying the projectile as it leaves the muzzle end of the weapon. These devices typically include an elongated tubular housing containing a series of baffles that define a plurality of successive internal chambers. These chambers serve to control, delay, and divert the flow, expansion, and exiting of the propellant gases, and also to reduce their temperature, so as to achieve a corresponding reduction in the noise produced by the propellant gases as they ultimately exit the device. The rear (e.g., proximal) ends of these suppressors typically include a mechanism for removably attaching the device to the weapon, and their front (e.g., distal) ends include an opening for the exit of the projectile, and are typically located sufficiently forward of the muzzle end of the weapon that they also can effectively function as a flash hider (e.g., a muzzle flash suppressor). 
     In one classification scheme, silencers for firearms can be divided into two groups. In one group, the gases that follow the bullet into the rear end of the silencer are stored for a short period of time in each of a plurality of successive expansion chambers so as to produce a controlled expansion of the propellant gases through each chamber, thereby reducing their temperature and pressure in successive, gradual stages. 
     In a second group, at least a portion of the propellant gases are partially diverted through a plurality of radial vents or passages disposed between inner and outer circumferential walls of the suppressor to one or more un-baffled, radially exterior “blast suppressor” chambers located in a back section of the device, before being introduced into the series of expansion chambers of a baffled “front section” of the device of the type described above. Although this “two-stage” sound suppression technique is relatively more complex to implement, it provides more opportunities to delay and cool the propellant gases, and hence, to reduce muzzle blast sound levels overall. 
     Existing suppressors have certain problems that can mitigate their operation and/or efficiency. For example, as those of skill in the art will understand, since a suppressor operates by controllably containing the hot, expanding combustion gases used to propel the projectiles of the weapon upon which it is used, with extended use of the device over time, particulate contaminates contained in the combustion gases will condense and be deposited over the interior surfaces of the device, including the surfaces of the baffles. These deposits include carbon from the burnt propellant, lead from the projectiles, and in the case of the use of “jacketed” projectiles, copper, Teflon, and/or molybdenum disulfide. While these deposits can usually be cleaned away with suitable solvents, they are typically hard and adhesive in nature, making it difficult or impossible to disassemble the device for cleaning without damaging its parts. 
     Another problem associated with certain suppressors occurs where front and rear ends of a suppressor are both implemented using end caps that are secured to a housing with threaded joints. The rear end cap typically includes an internally threaded bore that is used to screw the suppressor onto an adapter, e.g., a flash hider, a muzzle brake, or directly onto a muzzle of the associated firearm to secure the suppressor thereto. Unfortunately, this arrangement can complicate the removal of the suppressor from the firearm because, as the suppressor is unscrewed from the adapter or the muzzle, the torque exerted by the user on the suppressor housing can cause the rear end cap of the suppressor to unscrew from the housing, rather than from the adapter or muzzle of the firearm. This may cause the rear end cap to remain substantially fixed on the adapter or muzzle. As a result, the suppressor may separate and become difficult to detach completely from the firearm. 
     Another problem that can occur particularly with the “two-stage” type of silencers described above relates to the fact that the first stage, “blast suppressor” back sections of the devices typically experience substantially greater radial pressures and temperatures than the baffled front compartments of the devices during the firing of a single round through the device. While this does not ordinarily present a problem when the weapon is fired intermittently, with sufficient time allowed between rounds to permit the pressure and temperature within the back section to abate, it can present a problem with sustained firing of the weapon at a relatively high rate of fire, e.g., during sustained, full automatic fire of the weapon. In such instances, it is possible for the outer tubular housing of the device to fail prematurely, i.e., to “blow out,” due to the sustained local pressures and temperatures impinging directly thereon during such sustained, full automatic, high rates of fire. One unsatisfactory approach to solving this problem is to increase the overall thickness of the external housing of the suppressor. However, such an approach may significantly increase the weight of such suppressors and torque exerted on a weapon, thus hampering their usefulness. 
     Another problem with existing suppressors relates to their ability to function effectively as muzzle flash suppressors. While the distal, or exit end of a prior art silencer is typically disposed forward of the actual muzzle end of the weapon&#39;s barrel, it is nevertheless possible for the suppressor to exhibit a relatively large muzzle flash when a “first round” is fired through the device (e.g., when the suppressor has not been recently fired). “Second” and immediately subsequent rounds fired from the suppressor typically do not exhibit this relatively large muzzle flash. 
     Another problem with existing suppressors relates to the mechanisms used to couple them to firearms. Such mechanisms typically include an internal mounting pin disposed in the suppressor that engages in a slot at the end of an adapter, which can comprise a flash hider or muzzle brake mounted at the muzzle end of the barrel of the firearm to which the suppressor is to be removably coupled. This arrangement can be problematic for several reasons. For instance, the mounting pin is cumbersome to manufacture, is prone to breakage, and cannot be easily repaired. Further, both the pin in the suppressor and the corresponding slot in the adapter are typically positioned well within the suppressor and, therefore, are subject to a buildup of carbon, lead and copper during firing use, as described above, which can complicate disassembly and prevent proper alignment and/or seating of the adapter within the suppressor. 
     SUMMARY 
     In accordance with various embodiments provided by the present disclosure, sound suppressors and methods for making and coupling them to firearms are provided that overcome various drawbacks associated with existing devices. 
     In one embodiment, a firearm sound suppressor includes a housing; a baffle; and an inner sleeve adapted to be disposed within the housing and to substantially surround the baffle, the inner sleeve comprising: a sidewall adapted to slide against the housing to permit the inner sleeve with the baffle to be selectively inserted into and removed from the housing without the baffle contacting the housing, and a longitudinal split extending through the sidewall and between front and rear ends of the inner sleeve to permit the sidewall to flex to permit removal of the baffle from the inner sleeve. 
     In another embodiment, a method of maintaining a firearm sound suppressor includes sliding a sidewall of an inner sleeve against a housing to remove the inner sleeve from the housing while the inner sleeve substantially surrounds a baffle and without the baffle contacting the housing; exerting a force on the sidewall, wherein a longitudinal split extends through the sidewall and between front and rear ends of the inner sleeve to permit the sidewall to flex in response to the force; and removing the baffle from the inner sleeve while the sidewall flexes. 
     In another embodiment, a method of manufacturing a firearm sound suppressor includes providing at least one baffle; providing an inner sleeve comprising: a sidewall, and a longitudinal split extending through the sidewall and between front and rear ends of the inner sleeve to permit the sidewall to flex; exerting a force on the sidewall to cause the sidewall to flex; and inserting the baffle from the inner sleeve while the sidewall flexes. 
     In another embodiment, a firearm sound suppressor includes a housing comprising a front end and a rear end, wherein the rear end comprises a flange that partially encloses the rear end and defines a rear aperture; and a back end member disposed substantially within the rear end of the housing and comprising a rear surface disposed in abutment with an inner surface of the flange to prevent the back end member from passing through the rear aperture. 
     In another embodiment, a method of assembling a firearm sound suppressor includes inserting a back end member into a front aperture at a front end of a housing, wherein the housing comprises a flange at a rear end thereof that partially encloses the rear end and defines a rear aperture; and sliding the back end member to the rear end of the housing until the back end member is disposed substantially within the rear end of the housing and a rear surface of the back end member abuts an inner surface of the flange to prevent the back end member from passing through the rear aperture. 
     In another embodiment, a method of removing a firearm sound suppressor includes exerting rotational force on a housing relative to a barrel end of a firearm, wherein: the housing comprises a front end and a rear end; the rear end comprises a flange that partially encloses the rear end and defines a rear aperture; a back end member is disposed substantially within the rear end of the housing and comprising a rear surface disposed in abutment with an inner surface of the flange to prevent the back end member from passing through the rear aperture; and complementary anti-rotation features provided by the back end member and the flange engage with each other to prevent rotation of the back end member relative to the housing while the rotational force is exerted. 
     In another embodiment, a firearm sound suppressor includes a housing; an interior member disposed within the housing so as to define a chamber between an exterior surface of the interior member and an interior surface of the housing, the interior member comprising a lumen and a plurality of vents extending through the interior member between the lumen and the chamber, wherein the vents are adapted to pass combustion gases from the lumen to the chamber; and a blast deflector disposed between the vents and the interior surface of the housing, wherein the blast deflector is adapted to prevent the combustion gases from impinging directly on the interior surface of the housing. 
     In another embodiment, a method of operating a firearm sound suppressor includes receiving combustion gases at a lumen of an interior member disposed within a housing so as to define a chamber between an exterior surface of the interior member and an interior surface of the housing; passing the combustion gases from the lumen through a plurality of vents extending through the interior member between the lumen and the chamber, receiving the combustion gases from the vents at a blast deflector disposed between the vents and the interior surface of the housing; and preventing, by the blast deflector, the combustion gases passed through the vents from impinging directly on the interior surface of the housing. 
     In another embodiment, a method of manufacturing a firearm sound suppressor includes providing a housing; providing an interior member; attaching a blast deflector to the interior member; and positioning the interior member with the blast deflector within the housing so as to define a chamber between an exterior surface of the interior member and an interior surface of the housing, the interior member comprising a lumen and a plurality of vents extending through the interior member between the lumen and the chamber, wherein the vents are adapted to pass combustion gases from the lumen to the chamber, wherein the blast deflector is disposed between the vents and the interior surface of the housing, wherein the blast deflector is adapted to prevent the combustion gases from impinging directly on the interior surface of the housing. 
     In another embodiment, a firearm sound suppressor includes a housing; and an end plate disposed at a front end of the housing and comprising a bore extending therethrough, wherein the bore comprises a tapered portion that opens toward a front surface of the end plate, wherein the tapered portion has an included angle in a range of approximately 10 degrees to approximately 25 degrees, wherein the bore is adapted to pass a first round and first associated gases to reduce a size of a first muzzle flash caused by a firing of the first round by a firearm when the firearm sound suppressor is substantially at thermal equilibrium with a surrounding environment. 
     In another embodiment, a method of operating a firearm sound suppressor includes receiving a first round fired by a firearm when the firearm sound suppressor is substantially at thermal equilibrium with a surrounding environment; and reducing a size of a first muzzle flash associated with the first round by passing the first round and first associated gases through a bore of an end plate disposed at a front end of a housing of the firearm sound suppressor, wherein the bore extends through the end plate and comprises a tapered portion that opens toward a front surface of the end plate, wherein the tapered portion has an included angle in a range of approximately 10 degrees to approximately 25 degrees. 
     In another embodiment, a method of manufacturing a firearm sound suppressor includes providing a housing; providing a plurality of baffles adapted to be disposed within the housing; and creating a bore extending through an end plate adapted to be disposed at a front end of the housing, wherein the bore comprises a tapered portion that opens toward a front surface of the end plate, wherein the tapered portion has an included angle in a range of approximately 10 degrees to approximately 25 degrees, wherein the bore is adapted to pass a first round and first associated gases to reduce a size of a first muzzle flash caused by a firing of the first round by a firearm when the firearm sound suppressor is substantially at thermal equilibrium with a surrounding environment. 
     In another embodiment, a method of aligning a firearm sound suppressor includes inserting a front portion of a body of an adapter into a socket of the firearm sound suppressor; sliding a tab of the adapter into a slot disposed in an interior surface of the socket to rotationally align the firearm sound suppressor relative to a firearm; and contacting a plug of the adapter against the interior surface in a complimentary engagement, wherein the plug is provided by a frusto-conical external surface of a rear portion of the body, wherein the tab extends from the plug. 
     In another embodiment, an adapter includes a body having a front portion configured to be inserted into a socket of a firearm sound suppressor; a frusto-conical external surface substantially at a rear portion of the body and providing a plug configured to be received by a complementary interior surface of the socket; and a tab extending from the plug and adapted to be received by a slot disposed in the interior surface to rotationally align the firearm sound suppressor relative to a firearm. 
     In another embodiment, a firearm sound suppressor includes a housing; and a socket disposed in a rear section of the housing and configured to receive a front portion of a body of an adapter, wherein the socket comprises an interior surface configured to receive a plug in a complimentary engagement, wherein the plug is provided by a frusto-conical external surface of a rear portion of the body, wherein a slot disposed in the interior surface is adapted to receive a tab of the adapter to rotationally align the firearm sound suppressor relative to a firearm, wherein the tab extends from the plug. 
     The scope of the invention is defined by the claims, which are incorporated into this section by reference. A more complete understanding of embodiments of the present invention will be afforded to those skilled in the art, as well as a realization of additional advantages thereof, by a consideration of the following detailed description of one or more embodiments. Reference will be made to the appended sheets of drawings that will first be described briefly. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is an upper, rear, right side perspective view of a firearm sound suppressor in accordance with an embodiment of the disclosure. 
         FIG. 2  is a top plan view of the suppressor of  FIG. 1  in accordance with an embodiment of the disclosure. 
         FIG. 3  is a cross-sectional view of the suppressor of  FIG. 1 , as seen along the lines of the section  3 - 3  taken therein, showing a plurality of baffles disposed coaxially therein in accordance with an embodiment of the disclosure. 
         FIG. 4  is a cross-sectional view of a split inner tube of the suppressor of  FIG. 1  in accordance with an embodiment of the disclosure. 
         FIG. 5  is rear end elevation view of the suppressor of  FIG. 1 , as seen along the lines of the rear end view  5 - 5  taken in  FIG. 2  in accordance with an embodiment of the disclosure. 
         FIG. 6  is a front end elevation view of the suppressor of  FIG. 1 , as seen along the lines of the front end view  6 - 6  taken in  FIG. 2  in accordance with an embodiment of the disclosure. 
         FIG. 7  is a cross-sectional view through the suppressor of  FIG. 1 , as seen along the lines of the section  7 - 7  taken in  FIG. 2  in accordance with an embodiment of the disclosure. 
         FIG. 8  is a front end sectional view of the split inner tube of  FIG. 4 , as seen along the lines of the front end view  8 - 8  taken therein in accordance with an embodiment of the disclosure. 
         FIG. 9  is a right side elevation view of the suppressor of  FIG. 1 , shown coupled to the muzzle end of a barrel of a pistol in accordance with an embodiment of the disclosure. 
         FIG. 10A  is an upper, rear, right side perspective view of another firearm sound suppressor in accordance with an embodiment of the disclosure. 
         FIG. 10B  is an exploded perspective view of the suppressor of  FIG. 10A  in accordance with an embodiment of the disclosure. 
         FIG. 10C  is a cross-sectional view of the suppressor of  FIG. 10A , as seen along the lines of the section  10 C- 10 C taken therein, showing a plurality of baffles disposed coaxially therein in accordance with an embodiment of the disclosure. 
         FIG. 10D  is a cross-sectional view of the housing of the suppressor of  FIG. 10A , as seen along the lines of the section  10 C- 10 C taken therein, in accordance with an embodiment of the disclosure. 
         FIG. 10E  is an elevation view of a rear end of the housing of  FIG. 10D , as seen along the lines of the rear end view  10 E- 10 E taken therein in accordance with an embodiment of the disclosure. 
         FIG. 10F  is an elevation view of a front end of the housing of  FIG. 10D , as seen along the lines of the front end view  10 E- 10 E taken therein in accordance with an embodiment of the disclosure. 
         FIG. 10G  is a rear elevation view of a back end member of the suppressor of  FIG. 10A  in accordance with an embodiment of the disclosure. 
         FIG. 10H  is a cross-sectional view of the back end member of  FIG. 10G , as seen along the lines of the section  10 H- 10 H taken therein in accordance with an embodiment of the disclosure. 
         FIG. 10I  is a front elevation view of a front end plate of the suppressor of  FIG. 10A  in accordance with an embodiment of the disclosure. 
         FIG. 10J  is a cross-sectional view of the front end plate of  FIG. 10I , as seen along the lines of the section  10 J- 10 J taken therein in accordance with an embodiment of the disclosure. 
         FIG. 11A  is an upper, front, left side perspective view of a further firearm sound suppressor in accordance with an embodiment of the disclosure. 
         FIG. 11B  is a left side elevation view of the suppressor of  FIG. 1A  in accordance with an embodiment of the disclosure. 
         FIG. 12  is a left side cross-sectional view of the suppressor of  FIG. 11A , as seen along the lines of the section  12 - 12  taken in  FIG. 15 , with the housing omitted and showing an adapter for mounting the suppressor to a firearm in accordance with an embodiment of the disclosure. 
         FIG. 13  is a left side cross-sectional view of the suppressor of  FIG. 11A  similar to  FIG. 12 , with the baffles and the adapter omitted and showing the housing in accordance with an embodiment of the disclosure. 
         FIG. 14  is a front end elevation view of the suppressor of  FIG. 11A , as seen along the lines of the front end view  14 - 14  taken in  FIG. 13  in accordance with an embodiment of the disclosure. 
         FIG. 15  is a rear end elevation view of the suppressor of  FIG. 11A , as seen along the lines of the rear end view  15 - 15  taken in  FIG. 13  in accordance with an embodiment of the disclosure. 
         FIG. 16  is a front, left side perspective view of the back end member of the suppressor of  FIG. 13  in accordance with an embodiment of the disclosure. 
         FIG. 17  is a rear, right side perspective view of the back end member of the suppressor of  FIG. 13  in accordance with an embodiment of the disclosure. 
         FIG. 18  is an enlarged portion of the cross-sectional view of the back end member of the suppressor of  FIG. 13  in accordance with an embodiment of the disclosure. 
         FIG. 19  is a right side elevation view of the back end member of the suppressor of  FIG. 13 , showing a hollow cylindrical blast shield mounted concentrically thereabout in accordance with an embodiment of the disclosure. 
         FIG. 20  is a rear end elevation view of the back end member of the suppressor of  FIG. 13 , showing a slot at the rear end thereof in accordance with an embodiment of the disclosure. 
         FIG. 21  is a front end elevation view of the back end member of the suppressor of  FIG. 13  in accordance with an embodiment of the disclosure. 
         FIG. 22  is a front and left side perspective view of an example embodiment of a front end plate of the suppressor of  FIG. 11A  in accordance with an embodiment of the disclosure. 
         FIG. 23  is a front end elevation view of the front end plate of the suppressor of  FIG. 11A  in accordance with an embodiment of the disclosure. 
         FIG. 24  is a cross-sectional view of the front end plate of the suppressor of  FIG. 11A , as seen along the lines of the section  24 - 24  taken in  FIG. 23  in accordance with an embodiment of the disclosure. 
         FIG. 25  is a rear end elevation view of the front end plate of the suppressor of  FIG. 11A  in accordance with an embodiment of the disclosure. 
         FIG. 26  is an enlarged partial detail view of an example embodiment of a complementary engagement between a mounting tab disposed on the adapter of  FIG. 12  and a corresponding slot disposed in the back end member of the suppressor of  FIG. 11A  in accordance with an embodiment of the disclosure. 
         FIG. 27  is a left, lower side elevation view of an example embodiment of a flash hider, showing a ramped mounting tab disposed at a rear end circumfery thereof in accordance with an embodiment of the disclosure. 
         FIG. 28  is a cross-sectional view of the flash hider of  FIG. 27  in accordance with an embodiment of the disclosure. 
         FIG. 29  is a left side elevation view of an example embodiment of a muzzle brake in accordance with an embodiment of the disclosure. 
         FIG. 30  is a cross-sectional view of the muzzle brake of  FIG. 27 , showing a mounting tab disposed at a rear end circumfery thereof in accordance with an embodiment of the disclosure. 
         FIG. 31  is a right side elevation view of the suppressor of  FIG. 11A , shown coupled to the muzzle end of a barrel of a rifle in accordance with an embodiment of the disclosure. 
         FIG. 32  illustrates a suppressor having crenelations in accordance with an embodiment of the disclosure. 
     
    
    
     Embodiments of the present invention and their advantages are best understood by referring to the detailed description that follows. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures. 
     DETAILED DESCRIPTION 
     A firearm sound suppressor  10  is illustrated in the perspective, top plan, and cross-sectional views of  FIGS. 1-3 , respectively. As shown, the suppressor  10  includes an elongated substantially tubular housing  12 , front and rear end plates  14  and  16 , respectively, disposed at corresponding ends of the housing  12 , and baffles  18  disposed concentrically within the housing  12  and between the two end plates  14  and  16 . Although housing  12  and various other housings referred to herein are illustrated as having generally cylindrical shapes, such housings may be implemented using any shape (e.g., square, rectangular, triangular, polygonal, or others) in other embodiments as may be desired for particular applications. 
     In the particular embodiments illustrated in  FIGS. 1-3 , baffles  18  each contain a central aperture  20  and are disposed coaxially within the housing  12  such that they are distributed along the long axis thereof, with their central apertures  20  collectively defining an interrupted central lumen  22  within the housing  12 , through which a projectile (not illustrated) fired through the suppressor  10  travels. Adjacent ones of the baffles  18  define a series of combustion gas expansion chambers  24  therebetween. 
     The rear end plate  16  of the suppressor  10  can include a mechanism for removably coupling the suppressor  10  to a firearm  36 , such as that illustrated in  FIG. 9 . As illustrated in, e.g.,  FIGS. 3 and 5 , this coupling mechanism can include an internal thread (e.g., approximately ½ inch×28 threads per inch (TPI) in one embodiment) disposed in an aperture  26  in the rear end plate  16  that is adapted to engage a complementary external thread disposed on a muzzle end of the barrel  38  of the firearm  36 . However, as discussed below in connection with other suppressor embodiments, it should be understood that these or other mechanisms can be used to couple the suppressor  10  to the firearm  36  or other types of firearms as may be desired. 
     As illustrated in  FIG. 3 , the front and rear end plates  14  and  16  can be coupled to corresponding ends of the housing  12  by external threads  28  and  29 , respectively. In this regard, threads  28  and  29  may be disposed on plates  14  and  16  and adapted to engage with complementary internal threads disposed in corresponding ends of the housing  12 , so that the end plates  12  and  14  can be screwed into or out of the ends of the housing  12  for assembly and disassembly. As further illustrated in  FIG. 3 , the front end plate  14  may include a lip  15  configured to abut a front surface  17  of the housing  12  when the front end plate  14  is fully screwed into the housing  12 . Additionally, O-rings  30  and  31  can be disposed in corresponding circumferential grooves between an outer circumfery of the end plates  14  and  16 , respectively, and an inner circumfery of the housing  12  to seal the ends of the suppressor  10  and/or to provide insulation from vibration. Other end plate sealing and coupling mechanisms can be used, such as flat gaskets and/or complementary lugs and channels respectively disposed on various mating parts. 
     As may be seen in  FIG. 3 , the baffles  18  are typically arranged in a longitudinal “stack,” which can comprise a plurality of individual baffles separated by spacers, individual baffles with integral spacers, or a stack of baffles that are formed integrally with each other during their manufacturing process. For example, in some embodiments, baffles may be used such as those described in U.S. patent application Ser. No. 12/972,409 filed Dec. 17, 2010 which is incorporated herein by reference in its entirety. 
     As previously discussed, in known suppressor designs where gas expansion chambers communicate directly with interior wall surfaces of suppressor housings, particulate contaminates contained in the combustion gases confined in the device will condense out and be deposited over the entire interior surfaces of such suppressors. Such deposits are typically hard and adhesive in nature, making it difficult or impossible to disassemble such suppressors for cleaning without damaging its constituent parts. 
     However, such problems are readily overcome in the suppressor  10  of  FIGS. 1-9  by the provision of an inner tube  32  (e.g., also referred to as an inner sleeve or a baffle sleeve) made of a resilient material, such as aluminum, steel, a polymer, and/or other material, and having a sidewall and front and rear ends generally conterminous with corresponding ends of the housing  12 . Although inner tube  32  is illustrated as having a generally cylindrical shape, it may be implemented as an inner sleeve or baffle sleeve using any shape (e.g., square, rectangular, triangular, polygonal, or others) in other embodiments as may be desired for particular applications. 
     As illustrated in, e.g.,  FIGS. 3 and 7 , the inner tube  32  is disposed concentrically within the housing  12  and around the baffles  18  to act a barrier against the impingement of contaminants on the interior surface of the housing  12 . As illustrated in, e.g.,  FIGS. 4 and 8 , the inner tube  32  has a single longitudinal slot or split  34  extending through the sidewall of the tube and between the front and rear ends thereof so as to enable the sidewall of the tube  32  to flex in a generally radial direction in response to substantially radial force, and thereby permit the suppressor to be easily disassembled for cleaning. 
     For example, in one possible scenario, a heavily used suppressor  10  can be cleaned in the following manner. The front and rear end plates  14  and  16  are first removed from the corresponding ends of the housing  12 , e.g., by unscrewing them therefrom. The inner tube  32  and the stack of baffles  18  can then be easily slid from within the housing  12  (e.g., selectively inserted into and removed from the housing  12  in a slidable fashion), since the inner tube  32  has prevented adhesive combustion deposits from forming between baffles  18  and the inner surface of the housing  12 . In this regard, a substantially uncontaminated (e.g., clean) outer surface of inner tube  32  contacts a substantially uncontaminated (e.g., clean) inner surface of housing  12 , thus permitting the inner tube  32  to be easily slid out of the housing  12  while the stack of baffles  18  remains contained in the inner tube  32 . The stack of baffles  18  can then be removed from within the inner tube  32 , and various surfaces of the tubular housing  12 , the front and rear end plates  14  and  16 , the baffles  18 , and the inner tube  32  can then be easily cleaned of any combustion residue with a suitable gun solvent or other appropriate manner. 
     In circumstances where the inner surface of the inner tube  32  and outer surfaces of the baffles  18  are firmly adhered to each other by the combustion residue so as to form an integral assembly, the entire assembly can be slid out of the tubular housing  12  in a longitudinal direction, and the baffles  18  can then be easily removed from within the inner tube  32  by gently expanding the side wall of the inner tube  32  in the radial direction so as to break any adhesion between the inner tube  32  and the baffles  18  caused by any combustion residue therebetween and permit removal of the baffles  18  and cleaning of the baffles  18  and the inner tube  32 . Such expansion may be facilitated, for example, by providing the longitudinal slot  34  in the inner tube. In certain embodiments, the inner tube  32  may be constructed of a substantially flexible material (e.g., aluminum, flexible steel, or other materials) to permit expansion of the side wall of the inner tube in response to radial pressure exerted by a user. As those of skill in the art will appreciate, the various components of the suppressor  10  can be fabricated using a variety of methods and from a variety of materials, including heat treatable alloys of aluminum (e.g., anodized aluminum in one embodiment), steel (e.g., stainless steel in one embodiment), and/or titanium. 
     As illustrated in  FIGS. 1 and 2 , the housing  12  can be provided with substantially planar surfaces  11  disposed longitudinally along the housing  12 . In this regard, the suppressor  10  is illustrated as having eight planar surfaces  11  substantially uniformly distributed around the outer surface of the housing  12  to provide an outer profile that is substantially octagonal in shape. Other numbers of planar surfaces  11  may be provided in other embodiments to provide any other desired outer profile (e.g., hexagonal, polygonal, or other profiles). 
     In various embodiments, the planar surfaces  11  may be implemented to save weight. In this regard, in one embodiment, the suppressor  10  may exhibit a weight of approximately 2.6 ounces, a length of approximately 5.4 inches, and a diameter of approximately 1.0 inch. As shown in  FIGS. 2 and 7 , the planar surfaces  11  may be recessed such that the external portion of the housing  12  along the planar surfaces  11  exhibits a smaller external diameter than end plates  14  and  16 . The structural integrity of the housing  12  may be reinforced by unrecessed thicker portions  13  of the housing  12  located between adjacent planar surfaces  11 . In this regard, opposite unrecessed thicker portions  13  may collectively exhibit an external diameter substantially equal to that of the ends of the housing  12 . The structural integrity of the housing may also be reinforced by the thick walls of end plates  14  and  16  (shown in  FIG. 3 ). 
       FIG. 9  illustrates the suppressor  10  coupled to the muzzle end of the barrel  38  of a firearm  36 , e.g., a .22 caliber semiautomatic pistol. In several embodiments, suppressor  10  may be used with various types of weapons such as, for example, fully automatic rimfire weapons, .22 caliber pistols (e.g., Walther P22, Ruger 22/45, or others), rifles, or other types where appropriate. In several embodiments, suppressor  10  may be used with various types of ammunition such as, for example, .22 Long Rifle (LR), .22 Magnum (Mag), .17 Hornady Magnum Rimfire (HMR), or other types where appropriate. However, it should be understood that the suppressor  10  can also be used with firearms of different calibers and of different types, such as semiautomatic or fully automatic machine pistols or rifles. 
     As discussed, in certain suppressor implementations where front and rear end caps are threadably secured to a housing, the rear end cap may be susceptible to becoming unscrewed from the housing during removal of such suppressors from an adapter or firearm. Another embodiment of a sound suppressor  50  in accordance with the present disclosure is illustrated in  FIGS. 10A-J  that overcomes such problems. It will be appreciated that the suppressor  50  includes various features previously described with regard to the suppressor  10 . However, the suppressor  50  provides a different housing  52 , a different front end plate  54 , and a back end member  62 . 
     The housing  52  includes an open front end defining an aperture  56  and a partially closed rear end implemented with a flange  58  that partially encloses the rear end and defines an aperture  60 . The back end member  62  is disposed substantially concentrically within the housing  52 , at the rear thereof. The back end member  62  has a rear surface  64  that, when the suppressor  50  is assembled, is disposed in abutment with an inside surface  66  of the flange  58  of the housing  52  to prevent the back end member  62  from passing through the aperture  60 . In one embodiment, the rear surface  64  and the inside surface  66  may both be substantially flat surfaces, such that the rear surface  64  provides a plate adapted to contact the flange  58 . The back end member  62  also includes an internally threaded bore  26  extending through it, the bore  26  being disposed in coaxial alignment with the aperture  60  when the suppressor  50  is assembled. 
     The back end member  62 , the front end plate  54 , or both may include a circumferential groove  78  for an O-ring to effect a circumferential seal at a corresponding end of the housing  52  and/or to provide insulation from vibration, in a manner similar to that described with regard to the suppressor  10 . 
     The front end plate  54  inserts into the front end aperture  56 . The front end plate  54  has a bore  68  extending therethrough that is disposed in coaxial alignment with the bore  26  of the back end member  62 . The front end plate  54  also includes an external thread  29  disposed on a circumfery thereof. The thread  29  is configured to engage in a complementary internal circumferential thread  70  disposed in an interior surface of the front end of the housing  52 . 
     The bore  26  of the back end member  62  has an internal circumferential thread disposed in an interior surface thereof that is configured to engage a complementary external circumferential thread disposed on a circumfery of an adapter or a muzzle end portion of a barrel of an associated firearm in a similar manner as discussed with regard to the suppressor  10 . 
     In order to prevent the back end member  62  from rotating relative to the housing  52  during removal of the suppressor  50  from the muzzle of an associated firearm, the suppressor  50  is provided with complementary anti-rotation features provided by the flange  58  and the back end member  62  that are operable, when engaged with each other, to prevent the back end member  62  from rotating about a long axis of, and relative to, the housing  52 . 
     In one embodiment, the anti-rotation features include a rearwardly protruding boss  72  disposed on the rear surface  64  of the back end member  62  that is configured to engage the aperture  60  defined by the flange  58  at the rear end of the housing  52  in a complementary, axial slide-in engagement. 
     In one embodiment, the anti-rotation features may include one or more substantially radial protrusions  74  provided by the boss  72  and at least one corresponding complementary substantially radial slot  76  disposed in a circumfery of the aperture  60  defined by the flange  58 . In this embodiment, the radial protrusions  74  and the corresponding complementary radial slots  76  are disposed in substantial rotational symmetry about the long axis of the housing  52  in a star-like pattern, thereby enabling the boss  72  of the back end member  62  to be axially inserted into the aperture  60  at the rear end of the housing  52  in a plurality of angular orientations relative thereto. 
     When a user or machine exerts rotational force on the housing  52  or other portions of the suppressor  50  relative to a barrel end of a firearm to unscrew the suppressor  50  from the firearm, the radial protrusions  74  are respectively engaged in corresponding ones of the slots  76  and thereby prevent the back end member  62  from rotating relative to the housing  52 . Thus, the suppressor  50  can be detached completely from the associated firearm, e.g., for disassembly and cleaning, without the back end member  62  separating from the suppressor  50  or remaining attached to the associated firearm. 
     In one embodiment, the suppressor  50  may be assembled in the following manner, and may be disassembled in a reverse manner. The back end member  62  is inserted through the front aperture  56  and slid toward the flange  58  such that the rear surface  64  of the back end member  62  is disposed in abutment with the inner surface  66  of the flange  58  and the anti-rotation features  72  and  74  of the back end member  62  are respectively disposed in engagement with the anti-rotation features  60  and  76  of the flange  58 . The baffles  18  are disposed substantially concentrically within the inner tube  32 , and the sidewall of the inner tube  32  is compressed around the baffles  18  in a radial direction so as to form an integral assembly therewith. The integral assembly is then slid into the housing  52  in a longitudinal direction and into contact with the back end member  62 . In another embodiment, the back end member  62  and the integral assembly may be slid together in the housing  52  (e.g., the back end member  62  may contact or engage with the integral assembly before being inserted into the housing  52 ). The front end plate  54  is then inserted into the front end aperture  56  such that the back end member  62  and the integral assembly of the inner tube  32  and baffles  18  are pressed between the front end plate  54  and the rear end of the housing  52 . 
     The front end plate  54  may be screwed into the housing  52  through the engagement of threads  29  and  70 . Advantageously, because the engagement of the back end member  62  and the flange  58  causes the back end member  62  to be rigidly fixed with respect to the housing  12 , the front end plate  54  may be used as a single mechanism to tighten the entire suppressor  50  together. In this regard, as front end plate  54  is screwed into the housing  52 , the flange  58 , the back end member  62 , the baffles  18 , the inner tube  32 , and the front end plate  54  may all be tightened together. 
     A front surface  80  of the front end plate  54  can be provided with one or more indentations  82  configured to engage with an appropriate tool that may be used to screw the front end plate  54  into or out of the housing  52 . 
     As shown in  FIG. 10C , the front end plate  54  may include a substantially rounded surface  55  (e.g., in contrast to the lip  15  shown in  FIG. 3  for the suppressor  10 ). As a result, the front surface  80  of the front end plate  54  may be recessed within the housing  52  if desired. For example, because the front end plate  54  may be used as a single mechanism to tighten the entire suppressor  50  together, it may be desired in certain embodiments to screw the front end plate  54  well into the housing  52  until the front surface  80  is recessed within the housing  52  and behind the front surface  17  of the housing  52  to provide appropriate tension against the other components to hold suppressor  50  together tightly. In another embodiment, a substantially flat surface (e.g., substantially parallel to the length of the housing  52 ) may be used in the same manner in place of the substantially rounded surface  55 . 
     A further firearm sound suppressor  100 , is illustrated in the perspective, left side elevation, and top plan views of  FIG. 11A-12 , respectively. As shown, the suppressor  100  includes an elongated tubular housing  112 , a front end plate  114 , and a “stack” or plurality of baffles  118 , each containing a central aperture  120 , separated by spacers  119 , disposed coaxially within a front section of the tubular housing  112 , and distributed along a longitudinal axis thereof such that the central apertures  120  of the baffles  118  collectively define an interrupted central lumen  122  within the suppressor  100  and adjacent ones of the baffles  118  define gas expansion chambers  124  therebetween. 
     Unlike suppressor  10  discussed above, in lieu of a back end plate, the suppressor  100  includes a back end member  140  disposed in a rear section of the suppressor  100  and concentrically within the housing  112  so as to define a concentric blast suppression chamber  142  between an exterior surface of the back end member  140  and an interior surface of the tubular housing  112 . In one embodiment, back end member  140  may be implemented as a tubular female mounting adapter configured to receive an adapter  168  (e.g., a flash hider  168 ) to attach the suppressor  100  to a firearm  160  (shown in  FIG. 31 ) in a male-female engagement. In other embodiments, back end member  140  may receive other types of adapters such as muzzle brakes, other flash hiders, or other appropriate structures. 
       FIG. 13  is a cross-sectional view of the suppressor  100  similar to that of  FIG. 12 , but with the baffles  118  and the adapter  168  omitted and showing the housing  112 . The back end member  140  includes a central lumen  144  (see  FIGS. 13 ,  18  and  20 - 21 ) disposed in coaxial alignment with the central lumen  122  of the suppressor  100  and a plurality of vents  146  (e.g., radial passages) that extend through the back end member  140  between the lumen  144  and the blast suppression chamber  142  (see  FIG. 13 ). 
     Thus, it will be appreciated that the suppressor  100  may be implemented as a “two-stage” type of sound suppressor as discussed above, in which a portion of the propellant gases entering the central lumen  144  are partially diverted through the vents  146  disposed in the back end member  140  to the un-baffled, radially exterior blast suppressor chamber  142  located in the back section of the suppressor  100 , before being introduced into the series of baffled expansion chambers  124  in the front section of the suppressor  100 . 
     As discussed, in known two-stage suppressor designs, the “first stage,” or blast suppressor back sections of the devices typically experience substantially greater radial pressures and temperatures than the baffled front compartments of the devices during the firing of a single round through the device which can cause premature failure, especially with sustained, full automatic weapons fire. 
     The suppressor  100  avoids such problems by the provision of a blast deflector  148  that is disposed substantially concentrically about the back end member  140  at the location of the vents  146 . The blast deflector is effective to prevent hot gases (e.g., combustion gases) from impinging directly on the interior surface of the housing  112 . Instead, the hot gases flowing from the central lumen  144  through the vents  146  impinge on the blast deflector  148  and are deflected rearwardly into the blast suppression chamber  142 , as indicated by the arrows  150  in  FIG. 13 . 
     By positioning the blast deflector  148  over the vents  146 , a possible point of failure in the suppressor  100  may be reduced or eliminated. Moreover, by positioning the blast deflector  148  substantially at the rear of the suppressor  100  (e.g., proximate to the back end member  140 ), the housing  112  can be protected from the hottest gases that are closest to the muzzle of an associated firearm (e.g., before the gases experience further cooling as they travel further down the length of the suppressor  100 ). In addition, the use of the blast deflector  148  provides advantageous weight savings over other protection systems. For example, because the blast deflector  148  is relatively small in comparison with the size of the housing  112 , the blast deflector  148  may provide substantial weight savings over other possible protection techniques that might require increasing the overall thickness of the entire housing  112  as discussed. 
     In one embodiment, the blast deflector  148  may be a substantially tubular member (e.g., a continuous tubular ring or including one or more longitudinal splits  149  extending between front and rear ends of the blast deflector  148 ) implemented by a relatively thin sleeve having a longitudinal slit  149  (see  FIG. 19 ) extending through its side wall to enable it to expand radially for ease of assembly to the back end member  140 . In some embodiments, the blast deflector  148  may be attached to the back end member  140  (e.g., welded or brazed thereto) to hold the blast deflector  148  in place. In various embodiments, the housing  112 , the back end member  140 , and the blast deflector  148  can be fabricated efficiently from an alloy of aluminum or steel. Other configurations, assembly techniques, and/or materials can also be used where appropriate. 
     In other embodiments, any desired number of blast deflectors  148  may be positioned at other locations inside the housing  112  of the suppressor  100  (e.g., around various interior members such as back end member  140 , one or more baffles  118 , and/or other components). For example, a first blast deflector  148  may be provided at the back end member  140  of the suppressor  100  as shown, and one or more additional blast deflectors  148  may be provided to surround one or more baffles  118  located forward of the back end member for added protection for other portions of the housing  112  that are susceptible to receive hot gases (e.g., to prevent combustion gases passed through the interrupted central lumen  122  from impinging directly on the interior surface of the housing  112 ). 
     In other embodiments, the blast deflector  148  and/or similar structures may be used in other types of suppressors, e.g., those without a back end section  140  and/or blast suppression chamber(s)  142 , such as the suppressor  10  or others. For example, in the suppressor  10 , during a sustained, full automatic fire of the associated weapon  36  through the suppressor  10 , a similar blast deflector may be provided to protect against extraordinary pressures and temperatures experienced in the gas expansion chambers  24  that might lead to a local failure or blowout of an affected area of the tubular housing  12 . Such problems may be prevented in the suppressor  10  in a manner similar to that described above for the suppressor  100  by providing a blast deflector disposed concentrically within the housing  12  and about the affected portion of the baffles  18  that is operable to prevent hot gases flowing through the interrupted central lumen  22  and into successive ones of the gas expansion chambers  24  from impinging directly on the portion of the interior surface of the housing  12  surrounding the portion of the baffles  18  that are shielded by the blast deflector. 
     As discussed, it is common for the first round fired from a “cold” conventional suppressor (e.g., a suppressor that has not been recently fired) to exhibit a relatively large muzzle flash, while immediately succeeding rounds fired through the same suppressor typically do not exhibit as large a flash as that exhibited by the first round. 
     It has been determined by the inventor that this transient phenomenon results from circumstances where a suppressor through which a round has not been recently been fired is relatively “cool” and is filled with oxygen-rich ambient air. In this regard, the cold suppressor may be substantially at thermal equilibrium with its surrounding environment and its interior lumens and chambers are substantially filled with ambient air rather than combustion gases. When an initial round is then fired through the suppressor, the oxygen content of the gas between the inlet and outlet ends of the device is sufficient to sustain additional combustion of the oxygen within the length of the device itself, giving rise to a relatively large flash at the outlet end thereof. However, when subsequent rounds are then fired through the suppressor, the oxygen content of the gas in the device is relatively depleted and the interior lumens and chambers become substantially filled with combustion gases, such that the additional combustion of the oxygen within the device is no longer sustainable, and relatively smaller muzzle flashes are produced. 
     It has been further determined by the inventor that the heightened first round muzzle flash phenomenon discussed above can be substantially reduced or eliminated altogether by providing a suppressor with a front end plate  114  having a central bore  152  (e.g., a frusto-conical bore in one embodiment) extending therethrough and includes a taper that reduces the size of the first round muzzle flash by permitting additional ambient air to escape prior to combustion of the associated oxygen to reduce the overall size of the first round muzzle flash and/or by distributing the first round muzzle flash and at least some associated gases over a broader area when escaping the bore  152 , thus reducing the length of the first round muzzle flash. Such an implementation can reduce the size and/or length of the first round muzzle flash and is particularly useful to reduce the detection (e.g., visual, thermal, and/or infrared imaging) of automatic weapons fired from hidden or obscured locations. 
       FIGS. 22-25  illustrate one example of the front end plate  114  which may be provided at the front end of the tubular housing  112  of the suppressor  100  (see  FIGS. 11A-14 ). As may be seen in the cross-sectional view of  FIG. 24 , the bore  152  may be implemented with a tapered portion  151  and an untapered portion  153 . The untapered portion  153  extends from a back surface  154  of the plate  114  to meet the tapered portion  151  within an interior of the plate  114 . In one embodiment, the untapered portion  153  has a length of approximately 50 thousandths of an inch (e.g., 0.050 inches). The tapered portion  151  opens toward a front surface  156  of the plate  114 , and has an included angle θ. In various embodiments, included angle θ may be implemented in a range of approximately 10 degrees to approximately 25 degrees. In one embodiment, included angle θ is approximately 20 degrees. Other embodiments are also contemplated. For example, the untapered portion  153  may be implemented with different lengths and/or omitted altogether (e.g., the tapered portion  151  may extend entirely from the back surface  154  to the front surface  156  of the plate  114  in one embodiment). 
     Scallops  158  can be provided in the front and/or rear surfaces  156  and  154  to reduce weight. For example, scallops  158  can define recesses in the front surface and rear surfaces  156  and  154  of the plate  114 , such recesses being disposed between an outer rim or lip of the plate  114  and a central portion of the plate  114  providing the bore  152 . In the particular example embodiment illustrated in the figures, the front end of the bore  152  is substantially flush with the front surface  156  of the plate  114 , but other configurations are also contemplated. 
       FIG. 31  illustrates the suppressor  100  coupled to an associated firearm  160 , and in particular, to the muzzle end of a barrel  162  thereof. In the particular embodiment illustrated in  FIG. 31 , the associated weapon  160  comprises a rifle, viz., an M4 carbine, a variant of the standard M16A2 military assault rifle. However, as similarly discussed herein with regard to the suppressor  10 , the suppressor  100  can also be used with firearms of different calibers and different types, such as semiautomatic or fully automatic machine pistols or rifles. 
     As discussed, certain existing sound suppressor mounting mechanisms utilize an internal pin arrangement that is subject to failure and deposit build-up. Such existing mechanisms may also require complex manufacturing techniques. In contrast, the suppressor  100  may be implemented using a slot-and-tab mounting mechanism. Such an arrangement may be used to reliably mount the suppressor  100  to a firearm, such as the firearm  160  or others, such that the central lumen  122  of the suppressor  100  is coaxially aligned with the central lumen (not illustrated) of the firearm&#39;s barrel  162 , and such that the suppressor  100  is rotationally oriented (e.g., aligned) at a specific angular position relative thereto. Such an arrangement may also reduce the likelihood of problematic build-up of deposits and internal pin breakage over various existing mounting mechanisms. 
     As illustrated in  FIGS. 12-13 , the back end member  140  may be disposed in a rear section of the suppressor  100 , as described above. As further shown in  FIGS. 12 ,  17 - 18 ,  20 , and  26 , the back end member  140  includes a socket  164  having an interior surface with a tapered forwardly extending slot  166  (e.g., an index ramp) disposed therein. The interior surface of socket  164  is configured to receive a frusto-conical external surface of the adapter  168  in a complementary slide-in engagement. 
     The adapter  168  includes a plug  170  extending forwardly from a rear portion of a body thereof. The plug  170  has a frusto-conical external surface with a longitudinal alignment tab  172  extending forwardly therefrom such that as the front portion of the body of the plug  170  is inserted (e.g., slid) into the socket  164  followed by the rear portion of the body, the tab is received by slot  166  and the plug  170  contacts the interior surface of the socket. The engagement of tab  172  with slot  166  may thus rotationally align the suppressor  100  relative to a firearm. In addition, the complementary frusto-conical external surface of the plug  170  and the corresponding portion of the interior surface of the socket  164  permits plug  170  to be easily inserted into the socket  164  and reliably mate therewith. As illustrated in, e.g., the enlarged partial cross-sectional detail view of  FIG. 26 , a front end  173  of the tab  172  and a floor  167  of the slot  166  are correspondingly chamfered for ease of insertion of the former into the latter. 
     Advantageously, the slot  166  and the tab  172  (when engaged with the slot  166 ) are positioned substantially near the rearmost portion of the back end member  140  (e.g., on the end of the socket  164  thereof). As a result, the slot  166  and the tab  172  may be subject to less deposit build-up in comparison with prior suppressor mounting techniques that position various mounting engagement features substantially deeper within such prior suppressors. Also, because the tab  172  is provided on an external adapter (e.g., on a flash hider, muzzle brake, or other appropriate adapter), inadvertent damage sustained by the tab  172  (e.g., breakage, cracking, deformation, or other) does not prevent further usage of the suppressor  100  with another undamaged adapter. 
     The features described with regard to adapter  168  may be implemented in other types of adapters as may be desired for various implementations. For example,  FIGS. 27-30  illustrate various other adapters such as another flash hider  174  ( FIGS. 27-28 ) and a muzzle brake  176  ( FIGS. 29-30 ) that may be implemented in accordance with the described slot-and-tab mounting mechanism to attach the suppressor  100  to the firearm  160 . 
     The length of the tab  172  may also vary in different embodiments. For example, in flash hiders  168  and  174 , a long embodiment of the tab  172  is provided wherein the front end of the tab  172  extends forward of the front end of the frusto-conical surface of the plug  170 . In muzzle brake  176 , a short embodiment of the tab  172  is provided wherein the front end of the tab  172  is substantially conterminous with a front end of the frusto-conical surface of the plug  170 . Long and short embodiments of the tab  172  may be provided on any desired type of adapter, such as flash hiders, muzzle brakes, or others. 
     In one embodiment, the plug  170  and the alignment tab  172  may be formed, for example, by a machining operation directly into the muzzle end of the barrel  162  of the firearm  160 , thereby eliminating the need for a separate adapter to mount the suppressor  100  to the firearm  160 . 
     Where a separate adapter is used (e.g., such as flash hiders  168  or  174 , or muzzle brake  176 ), a mechanism may be provided for removably coupling the adapter to the barrel  162  of the firearm  160 . As illustrated in, e.g., the cross-sectional views of  FIGS. 12 ,  28 , and  30 , in one example embodiment, this coupling mechanism can comprise a bore  178  extending into the rear end of the adapter, the bore  178  having an internal thread configured to engage a complementary external thread (not illustrated) disposed on the muzzle end of the barrel  162  of the firearm  160 . 
     Additionally, a mechanism may be provided for retaining the back end member  140  in engagement with the adapter. For example, such a retaining mechanism may be implemented as described in U.S. Pat. Nos. 6,948,415, 7,676,976, and 7,946,069, all of which are incorporated by reference herein in their entirety. In this regard, an eccentric locking collar  180  may be rotatably disposed on the rear end of the back end member  140  and configured to engage with an opposing circumferential shoulder  182  disposed on the adapter as illustrated in  FIGS. 10 and 12 . 
     Thus, in one embodiment, a method may be performed for coupling the suppressor  100  to the muzzle end of the barrel  162  of the firearm  160  such that a central lumen  122  of the suppressor  100  is coaxially aligned with the central lumen of the barrel  162 . Such a method may include coupling an adapter to the muzzle end of the barrel  162  of the firearm  160 , as described above, sliding the back end member  140  into engagement with the adapter such that the external frusto-conical surface of the plug  170  is engaged in the corresponding internal frusto-conical surface of the socket  164  of the back end member  140 , and engaging the alignment tab  172  in the slot  166 . The retaining mechanism  180  can then be used to releasably secure the back end member  140  in engagement with the adapter. 
     Often, when a suppressor is attached to a firearm, a bayonet cannot be attached to the firearm. Because of this reason, as well as for other reasons, it is beneficial to provide a suppressor having features that are useful for self-defense, e.g., hand-to-hand combat. The features can define or at least partially define a weapon. It is also beneficial to provide a suppressor having features that are useful for self-defense even if a bayonet can be attached to the firearm along with a suppressor. It is also beneficial to provide a suppressor having features that are useful for various different tasks that can be performed in battlefield and police situations, such as breaking windows and clearing glass from the broken windows. 
       FIG. 32  illustrates a suppressor  1200  having crenelations in accordance with an embodiment of the disclosure. 
     Suppressor  1200  has features that, for example, can be useful for self-defense, e.g., can define a weapon, according to an embodiment. Such features can be useful in hand-to-hand combat, for example. The features can also be used for other activities such as breaking windows and clearing glass from the broken windows. 
     The suppressor  1200  can have a front end  1201  and a rear end  1202 . The front end  1201  can have at least one protrusion  1203  formed thereon. The front end  1201  can have any number of protrusions  1203  formed thereon. For example, the front end  1201  can have one, two, three, four, five, six, seven, eight, or more protrusions  1203  formed thereon. 
     The protrusions  1203  can have channels, cutouts, openings, or grooves  1207  formed therein. The grooves  1207  can run longitudinally (in a direction generally parallel with respect to the longitudinal axis  1602 ). The grooves  1207  can be generally circular, semi-circular, or of any other cross-sectional configuration. 
     The protrusions  1203  can be formed on a front end cap  1205  of the suppressor  1200 . An attachment system  1204  can be provided at the rear of the suppressor  1200 . A cylindrical housing  1206  can be disposed between the attachment system  1204  and the front end cap  1205 . The attachment system  1204  and/or the front end cap  1205  can be threaded to the cylindrical housing  1206 . The attachment system  1204  and/or the front end cap  1205  can be welded, adhesively bonded, riveted, held with fasteners (screws, bolts, etc.) or otherwise attached to the cylindrical housing  1206 . 
     Protrusions  1203  and/or any other desired structures can be formed on portions of the suppressor  1200  other than the front  1201  thereof. For example, protrusions  1203  can be formed on the housing  1206 . The protrusions  1203  or other structures can be configured for any desired purpose. For example, the protrusions  1200  can be for self-defense, can provide heat shielding, and/or can provide enhanced grip (such as while also providing heat shielding). 
     Although various features have been described with regard to particular suppressors  10 ,  50 ,  100 , and  1200 , it is contemplated that any of these features may be combined with each other in suppressors  10 ,  50 ,  100 , and  1200 , or other suppressors as may be appropriate in particular implementations. 
     As those of some skill in this art will by now appreciate, and depending on the particular application at hand, many modifications, substitutions and variations can be made in and to the materials, apparatus, configurations and methods of use and production of the firearm sound suppressors of the present disclosure without departing from the spirit and scope thereof. In light of this, the scope of the present disclosure should not be limited to that of the particular embodiments illustrated and described herein, as they are merely by way of some examples thereof, but rather, should be fully commensurate with that of the claims appended hereafter and their functional equivalents.