Patent Publication Number: US-2018038663-A1

Title: Suppressed upper receiver group having locking suppressor with through brake

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention generally concerns firearms, such as rifles, and more particularly concerns sound and flash suppressors that are mounted by threading a generally cylindrical suppressor device onto the threaded end of the barrel of a firearm. More particularly, the present invention concerns a suppressed upper receiver group including an upper receiver mechanism and cartridge gas energized auto-loading mechanism and a barrel for a tactical rifle wherein a sound and flash suppressor device is provided at the forward end or muzzle of the barrel. Even more specifically the present invention concerns a sound and flash suppressor having a generally cylindrical suppressor body or housing having a muzzle brake device that extends completely through the tubular body of the suppressor body and is designed to substantially eliminate baffle strikes by hot gunpowder residue and thus significantly minimize the need for frequent cleaning of suppressor components. 
     Description of the Prior Art 
     A significant number of firearm sound suppressor devices and flash suppressor devices, generally referred to as suppressors herein, have been developed over the years for use with firearms such as rifles, shotguns and handguns. In most cases the suppressors are attached to the barrel of a firearm, such as by threaded attachment. In some cases suppressor are constructed integrally with a firearm barrel so as to be a permanent component of the firearm. United States patents of general interest to current suppressor manufacture and use are U.S. Pat. Nos. 9,038,770, 9,115,949, 9,222,747 and 9,273,920. 
     Typically, a suppressor comprises an elongate tubular body that attaches in any suitable manner to a firearm barrel and provides for the movement of a projectile from the bore of a firearm barrel and through the tubular body of the suppressor. To facilitate sound suppression a number of internal baffles are typically positioned in stacked relation within a suppressor housing with baffle partitions disposed in axially spaced relation within the housing and with central openings in each baffle partition for projectile and propellant passage. A number of chambers that are defined between the internal baffles, causing the propellant gas to progress in serial but serpentine fashion through the multiple chambers, with its velocity being diminished as it progresses. 
     Propellant gas emitted from the bore of a gun barrel enters the much larger volume of the internal chamber of the tubular body and progresses serially from chamber to chamber, with the gas expanding and its pressure being diminished within each successive chamber. The partitions of the baffles of most suppressors are impacted by the hot propellant gas and are designed to reflect propellant gas and cause gas agitation within the chambers to slow the progress of gas transition through the suppressor and increase the dwell time and reduce the typically sharp and loud noise of the propellant gas being discharged from the suppressor. 
     Hot propellant gas striking the baffles and other components within a surpressor housing typically creates significant problems which until the present time there has been no reasonable solution. The hot propellant gas contains gunpowder residue in the form of small particulate that strikes baffle surfaces with significant velocity and energy. As the extremely hot propellant gas progresses through a sound and flash suppressor the hot gas and its gunpowder residue strikes the baffle members and causes the gunpowder residue to build up, i.e., essentially become plated, onto the surfaces of the baffle members. In a relatively short period of time the buildup of propellant residue will cause the suppressor to begin to lose its optimum operational characteristics, requiring personnel to accomplish disassembly of the suppressor and thorough cleaning of the baffle members and other internal components as well. Removal of this residue buildup is difficult and time consuming because of its essentially plated nature and requires cleaning equipment and expensive residue solvent to accomplish. It is clearly seen therefore that there is a need to provide a sound and flash suppressor mechanism that is designed to virtually eliminate the potential for significant buildup of propellant gas residue on the internal components of a firearm suppressor. The present invention accomplishes this benefit. 
     SUMMARY OF THE INVENTION 
     It is a principal feature of the present invention to provide a novel firearm having a suppressed upper receiver cartridge incorporating a sound and flash suppressor that substantially eliminates gunpowder residue strikes on the internal baffles within the suppressor, thus minimizing the frequency of residue cleaning that is required to maintain optimum performance thereof. 
     It is another feature of the present invention to provide a novel sound and flash suppressor for firearms having a muzzle brake device that is mounted to the threaded end of the barrel of a firearm, is received within the tubular housing of a suppressor and extends completely through the housing, with its forward end defining a pronged flash reducing tip surrounding the discharge port. 
     It is an even further feature of the present invention to provide a novel sound and flash suppressor for firearms that incorporates a collet clamping mechanism for releasably mounting a suppressor to a suppressor mounting adapter that is affixed to a firearm barrel and having ratcheted surfaces that ensure that the suppressor is maintained in tight and secure assembly with the mounting adapter without inadvertently becoming loose or separating from the suppressor mounting adapter. 
     It is also a feature of the present invention to provide a novel sound and flash suppressor for firearms that defines primary and secondary internal flow paths for cartridge gas flow to ensure that the internal pressure within the suppressor remains within operational limits for efficient sound suppression and substantially eliminating visible gunpowder flash. 
     Briefly, the various objects and features of the present invention are realized through the provision of a tactical firearm, such as an M-4, M-16 or AR-15 cartridge gas energized autoloading rifle having a suppressed upper receiver group having an upper receiver to which is mounted a barrel cartridge including a barrel, handguard and cartridge gas actuation system for cycling the bolt carrier and bolt to retrieve cartridges from a magazine, charge a cartridge chamber of the barrel with cartridges for firing and extract and eject spent cartridge cases following firing of each cartridge. The barrel cartridge of the upper receiver group is provided with a sound and flash suppressor device which is mounted to the threaded muzzle end of the barrel by means of a suppressor mounting adapter. The suppressor mounting adapter includes an integral propellant gas processing section of member that extends completely through the suppressor housing, being positioned with its external surface in close proximity with a central opening being collectively defined by each of several multiple baffle members that have fixed locations within the housing of the suppressor. The integral propellant gas processing section has transverse passages and bores that intersect a central bore through which projectiles and propellant gas pass during firing of the firearm. 
     The suppressor device is designed to divide the propellant charge from cartridge firing into primary and secondary flow paths to ensure low pressure conditions and prevent excessive back pressure or blow-back to the bore of the firearm barrel. This feature minimizes propellant gas discharge from the cartridge chamber of the barrel toward the shooter as the spent cartridge case is unseated. This feature also ensures that the spent cartridge cases, typically referred to as “brass” are quite clean, i.e., quite free of gunpowder residue, when extracted and ejected. 
     The suppressor mounting adapter includes a propellant gas processing geometry and projects through the suppressor housing, with an integral front flash hider end thereof projecting through a central opening in the forward closure wall of the suppressor housing. The gas processing suppressor mounting adapter ensures minimal buildup of propellant residue within the suppressor housing so that internal cleaning of the suppressor is required with much less frequency. 
     For efficient and secure suppressor mounting with the barrel of the firearm the rear or connecting end portion of the suppressor is provided with a generally circular array of tapered spring fingers defining a locking collet and being integral with the housing mounting adapter. The tapered spring fingers each have a normal release position and are flexed to a locking position by application of a closing force by a locking ring member. The locking ring member is captured to the housing mounting adapter and is tightened by rotation on a threaded section of the housing mounting adapter to apply closing and locking force to the spring fingers. The housing mounting adapter and the spring fingers of the locking collet each have ratcheting surfaces having ridges and grooves that engage when the collet is locked by tightening of the locking ring. The engaged ratcheting surfaces prevent the locking ring from inadvertently backing off, such as during handling of a firearm or as the result of the vibration that occurs during sustained firing of the firearm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the preferred embodiment thereof which is illustrated in the appended drawings, which drawings are incorporated as a part hereof. 
       It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
       In the Drawings: 
         FIG. 1  is an elevation view of a tactical firearm having a suppressed upper receiver group according to the present invention which includes a sound and flash suppressor having a dual gas flow path and a suppressor mounting adapter that extends completely through the suppressor housing; 
         FIG. 2  is an isometric illustration showing the suppressor structure and having a cut-away portion showing the interior components of the suppressor; 
         FIG. 3  is a longitudinal section view of the suppressor of  FIGS. 1 and 2  taken along line  3 - 3  of  FIG. 4 ; 
         FIG. 4  is a longitudinal section view of the suppressor mechanism with a forward portion of the suppressor mounting adapter thereof shown in full line; 
         FIG. 5  is a longitudinal section view showing the suppressor structure, with the suppressor mounting adapter separated from the firearm barrel; 
         FIG. 6  is a side elevation view showing the external configuration of the suppressor of  FIGS. 1-5 ; 
         FIG. 7  is an isometric illustration showing the sound and flash suppressor, emphasizing the rear or firearm barrel mounting feature of the present invention, with the collet locking cover removed to simplify an understanding of the invention; 
         FIG. 8  is another isometric illustration showing the rear mounting end portion of the suppressor in detail; 
         FIG. 9  is a partial isometric illustration showing the rear attachment end portion of the suppressor, with the suppressor mounting adapter partially received within the suppressor housing, such as during installation thereof; 
         FIG. 10  is an isometric illustration presenting the rear or mounting portion of the sound and flash suppressor of the present invention, particularly showing the internal locking collet thereof; 
         FIG. 11  is a fragmentary isometric illustration showing the spring fingers of the collet locking mechanism of  FIG. 10  in detail; 
         FIG. 12  is a partial isometric illustration showing a portion of a circular ratcheted surface for engagement with corresponding ratcheted surfaces of the spring fingers to ensure against rotation of the suppressor housing relative to the suppressor mounting adapter in the locked condition of the suppressor; and 
         FIG. 13  is an elevation view showing parts of the ratcheted surfaces of the spring fingers of the collet locking mechanism and a corresponding annular ratcheted surface of the suppressor mounting adapter. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring now to the drawings and first to the side elevation view of  FIG. 1 , a tactical firearm constructed according to the principles of the present invention is shown generally at  10  and is of the character identified as an M-4, M-16 or AR-15 auto-loading rifle. The M-4 and M-16 rifles are typically utilized by military and law enforcement personnel and have settings for semi-automatic fire, where the trigger of the rifle is pulled for discharge of individual rounds of ammunition and full automatic fire, where the rifle will continuously fire round after round as long as the trigger remains pulled. AR-15 tactical rifles are typically provided with a non-adjustable setting that limits the rifle to semi-automatic fire. AR-15 rifles are widely used by sportsmen for target shooting, hunting and a wide range of general shooting activities. 
     The firearm  10  has a barrel cartridge or upper receiver group shown generally at  12  in  FIG. 1  is generally defined by an upper receiver  13  having an internal bolt and bolt carrier mechanism for cycling ammunition during firing activity as is explained in detail below. The barrel cartridge has a firearm barrel  14  having a rifled central bore  15  through which bullets and residual cartridge gas pass during firing activity. The barrel defines a cartridge chamber within which cartridges are fed prior to firing and from which cartridge cases are extracted after firing has occurred. A handguard  16  of the barrel cartridge is positioned about the barrel member  14  with its wall structure surrounding and being spaced from the barrel structure to provide the user with protection against the rather high temperature that the barrel can reach especially during sustained or frequent firing activity. The handguard defines multiple openings through which air is caused to circulate by thermal convection to remove heat that is liberated from the barrel and maintain the handguard as cool as possible. 
     To the upper receiver is typically pivotally mounted a lower receiver mechanism or group  20  having a hand-grip  22 , a trigger guard  24  and a magazine receptacle  26  within which a box-type ammunition magazine  28  containing a supply of cartridges is releasably received. A pivot pin  30  is extended through pivot holes in the upper and lower receivers to establish the pivotal assembly and a locking pin  32  is extended through corresponding locking holes in the upper and lower receivers to secure the upper and lower receivers in operative assembly as shown in  FIG. 1 . To the lower receiver group  20  is typically mounted a gun-stock, which can be an adjustable gun-stock as shown at  18  to permit the gun-stock to be adjusted to a length that is desired by the shooter or to accommodate the firearm to persons of different body characteristics or a gun-stock that is non-adjustable. 
     A sound and flash suppressor, shown generally at  34 , is provided at the muzzle end  36  of the rifle barrel  14  as shown in  FIG. 3  and has an elongate, generally cylindrical tubular housing  38  having an intermediate section  40  and enlarged structurally enhanced end sections  42  and  44 . The intermediate section  40  defines a plurality of annular external ribs  46  that are provided to enhance the pressure containing capability of the tubular housing. The annular external ribs are roughened by providing annular bands of longitudinal grooves  48  and ribs  50  to enable ease of manual rotation of the suppressor housing, such as for tightening the housing with the suppressor mounting adapter during installation or loosening the housing and adapter connection for removal of the suppressor from the mounting adapter. 
     The suppressor housing  38  defines an internal propellant gas processing chamber  54  within which is positioned a generally cylindrical spacer member  58  having a cylindrical wall  60  that is maintained in spaced relation with an inner cylindrical wall surface  62  of the suppressor housing, thus defining a secondary propellant gas flow passage  64  in the form of an annulus that extends along the length of the suppressor housing. The secondary propellant flow passage is also defined by an annular space between a plurality of baffle members  56  and the inner cylindrical wall surface  62  of the suppressor housing  38 . Each baffle member  56  has an outer generally cylindrical wall  57  that is maintained in spaced relation with the inner cylindrical wall surface  62  of the suppressor housing by means of external annular spacer members  66 . Each of the external annular spacer members is interrupted by a number of outwardly facing slots or grooves  68  about the periphery thereof that cooperatively segmented spacing members with the spaces defining portions of the secondary flow passage of the suppressor. 
     The secondary propellant flow passage or path  64  conducts the propellant gas into an annular gas discharge chamber  70  in which the gas is subjected to further energy dissipating turbulence. The gas is then discharged from the annular gas collection and discharge chamber  70  via a circular port array having a multiplicity of secondary discharge ports  72  that are formed in a front wall structure  74  of a front closure member  76  of the suppressor housing. Each of the secondary discharge ports  72  is angulated toward the center-line of the suppressor mounting adapter  120  and the suppressor housing  38 . The front closure has a generally centrally located propellant gas discharge opening  75  that is of tapered configuration having its smallest dimension facing forward. The front closure member  76  defines a generally cylindrical extension  78  having an externally threaded section  80  that has threaded engagement with an internally threaded section  82  within the enlarged structurally enhanced end section  44  of the suppressor housing  38 . An annular seal member  84  is located within an annular groove in the front closure member  76  and serves to maintain a sealed condition between the suppressor housing  38  and the front closure member  84 . The secondary discharge ports  72  are each angulated inwardly so as to direct discharge jets of propellant gas toward the longitudinal center-line of the suppressor. 
     At the rear or connecting end of the sound and flash suppressor  34  the enlarged and structurally enhanced rear or connecting end section  42  of the suppressor housing  38  defines an internally threaded section  86  that is threadedly engaged with an externally threaded section  88  of a housing mounting adapter  90 . A rearward extension  92  of the enlarged end section  42  of the suppressor housing overlies an annular seal groove  94  containing an annular sealing member that maintains sealing of the suppressor housing with respect to the housing mounting adapter  90 . The circular rear end  96  engages an annular positioning shoulder  98  to accurately position the tubular suppressor housing with respect to the housing mounting adapter  90 . 
     The extreme rear end portion of the housing mounting adapter  90  is provided with a plurality of moveable spring locking fingers  100  which are present in the section views  3 - 5  and are best seen in  FIGS. 7-9, 10 and 11 . Each of the spring locking fingers is integral with the housing mounting adapter  90 , being connected with the housing mounting adapter by means of a small connector section  102  which is flexible and spring-like. The flexible connector section permits the spring locking fingers to be moved inwardly to locking positions by application of an external force. When the external force is removed, the spring fingers will be returned to their non-locking positions. Flexibility of the spring fingers is enhanced by slots  104  and  106  that extend from the sides of each spring locking finger. 
     A locking ring  108  is maintained captive with said housing mounting adapter  90  by an annular retainer wall  110 . The locking ring has an internal thread section  112  that is received by an external thread section  114  of the housing mounting adapter to permit the locking ring  108  to be threaded onto the housing mounting adapter. The locking ring defines a rearwardly extending generally conical actuating portion  116  that engages and actuates the locking fingers to their locking positions when the locking ring is tightened on the housing mounting adapter. When the locking ring is rotated in the opposite rotational direction the generally conical actuating portion  116  is moved away from the locking fingers, allowing the small spring-like connector sections  102  to move the locking fingers back to their non-locking or release positions. When the locking fingers are at their release positions the suppressor housing  38  and its housing mounting adapter  90  can be rotated in a direction releasing the housing and housing adapter for removal from the suppressor mounting adapter  120 . 
     A suppressor mounting adapter  120  defines a rearwardly oriented barrel mount receptacle  122  having an internally threaded section  124  that receives the externally threaded muzzle end of the firearm barrel  14  and defines an internal stop shoulder  126  against which is seated a positioning shoulder of the barrel. The suppressor mounting adapter defines external wrench flats  127 , enabling a simple wrench to be employed to apply sufficient torque force to the suppressor mounting adapter to establish its threaded connection with the firearm barrel  14 . 
     As best shown in  FIGS. 9 and 12  the suppressor mounting adapter  120  defines an annular rim  119  having a roughened or ratcheted external surface  121  that is defined by a 360°,  130  tooth arrangement. However, it should be borne in mind that roughened surfaces of other character may be employed without departing from the spirit and scope of this invention. Correspondingly, the inner gripping surfaces of each of the spring locking fingers  100  define matching roughened or ratcheted surfaces  123  that establish locking engagement with the roughened or ratcheted external surface  121  which the spring locking fingers have been forced inwardly to their locking positions by the locking force of the locking ring  108 . When the external and internal ratcheted surfaces are engaged the suppressor housing is firmly locked in place with respect to the suppressor mounting adapter and cannot be rotated for tightening or loosening. 
     Centrally of the suppressor mount receptacle  122  extends a bore  128  through which a projectile, such as a bullet, and cartridge gas generated by combustion of the powder charge of a cartridge pass upon discharge or firing of a cartridge by the firearm. 
     It is necessary to ensure that the suppressor mechanism  34  remains positively aligned with respect to the bore of the barrel  14  at all times. This feature is achieved, as shown in  FIGS. 3-5  by spaced externally tapered sealing surfaces  130  and  132  that are engaged for sealing and alignment by correspondingly spaced tapered sealing surfaces  134  and  136  within the housing mount adapter  90 . Between these spaced pairs of tapered sealing surfaces is located an external thread section  138  of the suppressor mounting adapter  120  and an internal threaded section  140  of the housing mounting adapter  90 . When the thread connection of the external and internal thread sections  138  and  140  are made up and the spaced pairs of tapered sealing surfaces are in sealing engagement the thread connection between the suppressor mounting adapter and housing mounting adapter is protected from contamination by the constituents of the propellant being processed by the suppressor. Additionally, the spaced pairs of tapered sealing surfaces have a back-sealing capability and serve to prevent propellant gas and residue from being forced rearwardly within the suppressor by propellant pressure to exit the suppressor in a direction toward the shooter. 
     Each of the baffle members  56  defines an annular tapered reflecting wall  142  having an inner end portion  144  defining a relatively large central opening  146  as compared with most suppressor designs. The edges defining the large central opening are located in close proximity to the outer peripheral surface  151  of the propellant gas processing section. The suppressor mounting adapter  120  has a port  154  at the intersection of the axial bore  128  shown generally at  150  that is an integral part of the suppressor mounting adapter  120  and extends throughout the axial length of the suppressor housing  38 . The forward end portion  148  of the propellant gas processing section  150  has a flash hider geometry that is defined by tapered projections  152  that surround a port  154  at the forward terminus of the axial bore  128 . The flash hider geometry is in the form of an open, angled, four-prong flash reducing tip reduces the small residual muzzle flash to near invisibility. The axial bore  128  is of slightly greater diameter as compared with the diameter of the bore of the firearm barrel, thus permitting projectile travel through the axial bore  128  without contact of the projectile with the wall surface of the axial bore upon discharge of the firearm. 
     Transverse passages  160  and  162  extend through the propellant gas processing section  150  and communicate the propellant processing chamber  54  with the central bore  128  so that propellant gas is caused to enter the processing chamber  54  at greater volume and slightly higher pressure via transverse passage  160  as compared with the volume of propellant gas entering the processing chamber  54  via the transverse passage  162 . Some of the propellant pressure entering the propellant gas processing chamber  54  via the transverse passages  160  and  162 , because of the higher pressure in chamber  54 , will enter an annular bypass chamber  164  via a generally circular array of bypass ports  166 . The annular bypass chamber  164  is in the form of an annular groove that is defined by an axially spaced annular rim  165  that is supported by a generally cylindrical rim support  167 . An annular seal member  169  is contained within an annular seal groove in the housing mounting adapter as shown in  FIG. 5  and maintains a seal between the housing mounting adapter and suppressor mounting adapter. 
     Propellant pressure within the annular bypass chamber  164  will enter the secondary propellant flow passage or bypass passage  64  that is defined by the annular space between the cylindrical walls of the spacer and baffle members and the inner cylindrical surface of the housing  38  as mentioned above. From the secondary propellant flow passage the propellant gas is conducted past the multiple restrictions defined by the multiple slots and grooves  68  and enters an annular collection and discharge chamber  70 . From the chamber  70  the propellant gas, now at a much reduced pressure, is directed through the circular array of secondary angulated discharge ports  72 . 
     The axial bore  128  and the series arrangement of propellant gas processing chambers  54  and  172  serve to establish the primary flow path for gas propagation through the suppressor mechanism for conducting a majority of the propellant gas to the ejection port  154 . The processed gas that is diverted into the secondary flow path decreases the gas flow and pressure that flows to and is discharged from the primary flow path, thereby ensuring decreased discharge pressure and prolonged discharge pulse, significantly decreasing the sound output of the suppressor. 
     Other transverse passages  168  are spaced along the length of the axial bore  128  and serve to conduct propellant gas from the central bore  128  into various annular chambers such as  170  and  172  that are defined between the annular tapered reflecting walls  142  of adjacent baffle members  56 . The transverse passages and a number of transverse bores  174 , also intersecting the oriented at 90° with respect to the transverse passages, function to create turbulence within each of the annular gas processing chambers that surround central bore  128  and to permit controlled flow of propellant gas from chamber to chamber serially toward the discharge end of the suppressor. Each of the segments  156  of the gas processing forward portion of the suppressor mounting adapter  120  reflect propellant gas energy and thus serve to further create turbulence within the gas processing chambers of the suppressor. This turbulence slows the propagation of gas flow through the suppressor mechanism. Various annular chambers such as  170  and  172  of  FIG. 4  receive propellant pressure from the central bore  128  via the transverse passages  160 - 162  and the transverse bores  174 . 
     As shown in  FIG. 4 , within the forward end portion of the suppressor  34  two of the baffle members are oppositely positioned and define a large propellant gas processing chamber that is partitioned  177  by a generally planar circular wall  178  to define propellant gas accumulation chambers  176 . The generally planar circular wall  178  has a central opening  180  having a circular edge located in close proximity to the segment  182  of the gas processing forward portion of the suppressor mounting adapter  120 . It is evident that a small amount of propellant gas is forced by pressure to flow through the small spaces between the inner surfaces of the tapered reflecting walls of the baffles and the generally planar circular wall  178  and the external surfaces of the various segments of the gas processing forward portion of the suppressor mounting adapter  120 . This feature further retards gas flow through the suppressor, lowering gas pressure, extending suppressor dwell time and minimizing both sound and flash. 
     As mentioned above, the baffles of the suppressor of this invention are essentially protected against buildup of gunpowder residue during use of the suppressor. The propellant gas contains residue particulate that has greater mass than the mass of the gas. As the gas is diverted from the central bore  128  the particulate, having greater mass, tends to resist being diverted and thus continues to be moved through the central bore to the discharge port  154 , rather than being diverted into the gas processing chambers and impacting the baffle surfaces. This feature causes the baffle surfaces to remain clean for longer periods of time so that suppressor down time for cleaning is minimized. 
     When the housing  39  and the housing mounting adapter  90  are unthreaded from the suppressor mounting adapter  120  and removed the gas processing forward section  150  of the suppressor mounting adapter  120  remains as a portion of the barrel assembly of the firearm and is completely exposed. Being exposed and supported by the barrel, the suppressor mounting adapter, and particularly its forward section  150  are easily cleaned such as by means of a wire brush that is perhaps supplemented by a solvent for any buildup of gunpowder residue. 
     Since the internal baffles within the suppressor housing collectively define a relatively large central passage the baffles can be easily cleaned of gunpowder residue, such as by means of a rotary wire brush that is rotated within the large central passage and may be driven by an electrically powered rotary drill. In field conditions a cylindrical wire brush may be used alone or in combination with a solvent to easily and efficiently remove the slight accumulation of the gunpowder residue that may exist. Since the baffles will have minimal buildup of gunpowder residue as explained above, cleaning of the baffles is typically simple and relatively easy to accomplish. 
     In view of the foregoing it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus disclosed herein. 
     As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its spirit or essential characteristics. The present embodiment is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.