Patent Abstract:
Provided is a firearm noise suppressor for use with a muzzle brake of the type having a body and a substantially conical wall therein together defining an inner chamber and a substantially open forward end. The noise suppressor includes a housing that is removably attachable at a rearward end to the forward open end of the muzzle brake. The housing includes a peripheral wall and a forward end wall having an outlet sized and positioned to allow a projectile to pass. At least one baffle is positioned in the housing and defines at least two inner chambers within the housing when attached to the muzzle brake.

Full Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 14/719,861 filed May 22, 2015, and claims priority to and the benefit of U.S. Provisional Patent Application No. 62/050,478, filed Sep. 15, 2014. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to a device, attachable to the open forward end of a Krinkov-type muzzle brake, for providing a modular firearm noise suppressor or silencer. 
       BACKGROUND OF THE INVENTION 
       [0003]    Muzzle brakes or recoil compensators are known, which redirect propellant gases to counter recoil when a firearm is fired. Likewise, a flash suppressor is a known device attached to the muzzle of a rifle that reduces its visible signature while firing by cooling or dispersing the burning gases that exit the muzzle, a phenomenon more often associated with carbine length weapons. A number of different flash suppressing designs have been used over the years. The simplest is a cone placed on the muzzle end of the barrel, which was used during World War II on jungle-combat versions of the Lee-Enfield, No. 5 variant, or the M1 Carbine. Pronged or birdcage type flash suppressors have also been used, which radially disperse burning gases rapidly exiting the muzzle. 
         [0004]    Another type of flash suppressor, which may also aid in reliability by increasing back pressure, is patterned after the Krinkov brake found on the Soviet AK74SU submachine gun. The Krinkov brake provides an expansion chamber with a cone-shaped exit nozzle. Other later devices, such as the KX3 flash suppressor sold by Noveske Rifleworks, LLC of Grants Pass, Oreg., have rearranged the Krinkov brake to position a chamber around the cone, shortening the overall length of the muzzle device. A Krinkov-type brake is not considered a noise suppressor, also known as a silencer, because, although it has a chamber, it simply redirects the blast that causes sound pressure waves forward and does not have a separate end cap or wall forward of the inner cone. 
         [0005]    Under United States law, flash suppressors, muzzle brakes, and compensators are treated differently from noise suppressors. Firearms noise suppressors are regulated as firearms under the National Firearms Act of 1934 and require registration and payment of a transfer tax. Although some states regulate the use of flash suppressors, the use of muzzle brakes and compensators generally are not restricted. 
         [0006]    Many types of firearm noise suppressors are available, including some that attach to or over various muzzle devices, including, and combination devices. All of those muzzle devices break up or redirect propellant gasses exiting the muzzle laterally. A Krinkov-type brake inherently has a large diameter forward opening or “bell” that is not conducive to attachment of a noise suppressor. The present invention is intended to improve on these designs and to provide a modular noise suppression unit that can be attached to the forward end of a Krinkov-type brake. 
       SUMMARY OF THE INVENTION 
       [0007]    Disclosed is a firearm noise suppressor for use with a muzzle brake of the type having a body and a substantially conical wall therein together defining an inner chamber and a substantially open forward end, also commonly known as a Krinkov-type brake. The noise suppressor includes a housing that is removably attachable at a rearward end to the forward open end of the muzzle brake. The housing includes a peripheral wall and a forward end wall having an outlet sized and positioned to allow a projectile to pass. At least one baffle is positioned in the housing and defines at least two inner chambers within the housing when attached to the muzzle brake. The at least one baffle may include a substantially conical portion that extends at least partially into the open front end of the muzzle brake. 
         [0008]    Other aspects, features, benefits, and advantages of the present invention will become apparent to a person of skill in the art from the detailed description of various embodiments with reference to the accompanying drawing figures, all of which comprise part of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0009]    Like reference numerals are used to indicate by parts throughout the various figures of the drawing, wherein: 
           [0010]      FIG. 1  is an isometric view of an embodiment of the present invention; 
           [0011]      FIG. 2  is an exploded isometric view of the device showing a protective ring and a glass break attachment that can attached to the forward end of the device; 
           [0012]      FIG. 3  is an isometric view showing the protective ring attached; 
           [0013]      FIG. 4  is an isometric view showing the glass break attachment installed; 
           [0014]      FIG. 5  is a view similar to  FIG. 1 , shown in longitudinal section; 
           [0015]      FIG. 6  is a side plan view shown in longitudinal section and attached to the muzzle portion of a barrel; 
           [0016]      FIG. 7  is a rear isometric view of the inner body member and front cover member with the protective ring attached; 
           [0017]      FIG. 8  is an exploded isometric view of the muzzle brake, protective cover, and noise suppressor of the present invention; 
           [0018]      FIG. 9  is an isometric view if the noise suppressor installed on the muzzle brake; and 
           [0019]      FIG. 10  is a longitudinal section view of the noise suppressor installed on the muzzle brake. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    With reference to the drawing figures, this section describes particular embodiments and their detailed construction and operation. Throughout the specification, reference to “one embodiment,” “an embodiment,” or “some embodiments” means that a particular described feature, structure, or characteristic may be included in at least one embodiment. Thus appearances of the phrases “in one embodiment,” “in an embodiment,” or “in some embodiments” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the described features, structures, and characteristics may be combined in any suitable manner in one or more embodiments. In view of the disclosure herein, those skilled in the art will recognize that the various embodiments can be practiced without one or more of the specific details or with other methods, components, materials, or the like. In some instances, well-known structures, materials, or operations may not be shown or described in detail to avoid obscuring aspects of the embodiments. 
         [0021]    Referring to the various figures of the drawing, and first to  FIGS. 1-6 , therein is shown at  10  a flash suppressing muzzle brake device of the present invention. The device  10  includes a substantially cylindrical main body housing  12  with a rear end portion  14  adapted to be secured, such as by threading, onto the muzzle of a firearm barrel  16  (shown in  FIG. 6 ). The rear portion  14  may be internally threaded to match threads provided at the muzzle end of a barrel  16  and may include flats  18  to facilitate tightening the main body housing  12  to the threaded connections. If desired, a pin  20  may be used to permanently secure the device  10  to the barrel  16 . 
         [0022]    The device  10  includes an inner body member  22  having a substantially conical forward portion  24  and a rear portion  26  provided with a plurality of elongated radial ports  28 . The inner body member  22  is held in place in an inner chamber  30  of the main body housing  12  by a front cover member  32 . When assembled, the inner chamber  30  is defined by the main body housing  12 , the exterior of the inner body member  22 , and the front cover member  32 , as best seen in  FIGS. 5 and 6 . 
         [0023]    The front cover member  32  may include a series of external threads  34  configured to match a series of internal threads  36  on the interior of the main body housing  12 . The front cover member  32  is configured on the inside to receive and support a forward rim  38  of the cone portion  24 . The main body housing  12  may also include an internal annular recess  40  adjacent the rear end portion  14  to receive the rear portion  26  of the inner body member  22 . When the front cover member  32  is threaded into engagement with the main body housing  12 , the inner body member  22  is secured in compression therebetween, as shown in  FIG. 6 . Specifically, the inner body member  22 , provides a passageway axially aligned with the bore  42  of the firearm barrel  16  when mounted. At the rear portion  26  of the inner body member  22  there is a chamber area  44  into which a projectile enters as it first exits the muzzle of the firearm barrel  16 . The chamber area  44  includes a plurality of radial ports  28  which control the rapidly expanding and high pressure gases being ported into the inner chamber  30  of the main body housing  12 . At least a portion of the muzzle blast impacts a rearward facing annular wall  46  at the forward end of the chamber area  44 . The radial ports  28  may be in the form of elongated slots, which, if desired, may extend substantially the full axial length of the rear portion  26  and be opened at the rearward most end. Also if desired, the length of the radial ports  28  may be angled or helically configured in the direction of rotation of the exiting projectile. For example, the helical orientation of the radial ports  28  may be made to correspond with the twist rate and direction of the rifling (not shown) in the bore  42  of the firearm barrel  16 . The high pressure flow of gasses passing through the radial ports  28  into the inner chamber  30  of the main body housing  12  impacts forward walls of that chamber  30  to partially counteract the recoil forces of the firearm. 
         [0024]    Forward of the chamber area  44  and in axial alignment with the bore  42  of the barrel  16 , is a passageway  48  which is sized to be only slightly larger in diameter than the projectile to be fired from the barrel  16 . The passageway  48  diameter should be kept as small as practical, while avoiding possible contact with the projectile. Forward of the passageway  48  is the conical portion  24  of the inner body member  22  defining a substantially conical chamber  50  with a fully open forward end  52 . As high velocity gases pass through the central passageway  48  and enter the conical chamber  50 , the stream is pulled toward the conical interior walls by the Coanda Effect (the tendency of a fluid jet to be attracted to a nearby surface). This causes the high velocity stream of gases to expand rapidly in cross-sectional area, which results in a corresponding rapid drop in fluid stream pressure and dissipation of the burning gasses that cause muzzle flash. 
         [0025]    The forward end of the front cover member  32  may be made with an annular series of spikes  54 , which provide a crenellated strike surface on the muzzle device  10 . If desired, a front cover ring  56  may be provided to cover the spikes  54  to guard against inadvertent contact with or injury to nearby persons or objects. The cover ring  56  may be internally threaded  58  to correspond with the external threads  34  of the front cover member  32 . Also if desired, at least a portion of the exterior surface of the front cover ring  56  may be provided with knurling  60  to facilitate grip when removing. Alternatively, a glass brake attachment  62  may be threaded on to the front cover member  32 . The glass break attachment  62  provides one or more forwardly-extending elongated tines  64  with hardened, sharp ends that can be used as an impact tool. 
         [0026]    Referring now in particular to  FIG. 7 , if desired, the rearward edge of the front cover member  32  may be provided with one or more tabs  66  or notches to provide grip in the event the external threads  34  of the front cover member  32  become stuck with the internal threads  58  of the front cover ring  56  (shown) or the glass brake attachment  62  (not shown). 
         [0027]    Also if desired, a series of dimples  68  or depressions may be formed over at least a portion of the outer surface of the main body housing  12  in order to increase the surface area for enhanced heat dissipation. 
         [0028]    Referring now to  FIGS. 8-10 , therein is shown at  70  a firearm noise suppressor that is mountable directly to the forward end of a muzzle brake  10  of the type described above. The device  70  includes a tubular body  72  with an open rear end  74  and a forward wall or end cap  76 . The body  72  may be provided with interior threads  78  adjacent the open rear end  74  that will mate with the external threads  34  on the front cover member  32  of the muzzle brake device  10 . As shown in  FIG. 8 , the suppressor  70  may be attached in lieu of the front cover ring  56  or other assessory for the muzzle brake device  10  and the body  70  may be sized to match the size and shape of the main body housing  12  of the brake  10 . 
         [0029]    Because the tubular body  72  of the suppressor  70  does not include any rear wall or end cap, it cannot be mounted directly to the muzzle of a firearm barrel and is incomplete to function as a firearm noise suppressor. Other types of muzzle brakes to which other firearm noise suppressors may be mounted include lateral ports through which propulsion gases are diverted and expelled. For this reason, suppressors that fit over such muzzle brakes must be designed to attach rearward of those lateral ports in order to contain the laterally-diverted gas flow. One such example is shown in U.S. Patent Application Publication No. 2013/0340313, published Dec. 26, 2013. The Krinkov-type muzzle brake device  10  described above includes only one, enlarged and forwardly-directed opening through which propulsion gases are expelled. In the form described above, the muzzle brake  10  does not reduce the sound of the firearm discharge, but merely redirects it in a forward direction. 
         [0030]    The interior of the tubular body  72  includes one or more baffles which divide the interior into a plurality of chambers  82  behind the front wall or end cap  76 . Each of the baffles  80  and the forward wall  76  includes a central opening  84 ,  86  axially aligned with the central passageway  48  and bore  42  of the firearm barrel  16  so that a projectile expelled from the barrel  16  is allowed to pass closely, but without interference or contact. A wide variety of shapes, styles or designs may be used for the baffles  82  in the present invention. The exact design or number of the baffles  82  is not pertinent to the present invention, only their position within the tubular body  72 . Likewise, the length and/or diameter of the tubular body  72  may be varied as necessary to accommodate a selected number or size of baffles, depending on the caliber of the firearm on which it is to be used and the degree of noise suppression desired. 
         [0031]    If the muzzle brake  10  includes a portion that projects forwardly of the location of the exterior threads  34 , the tubular body  72  must extend sufficiently rearward of the baffles  80  in order to attach and accommodate the forward projection, as shown in the illustrated embodiment. At the same time, because the forward end of a Krinkov-type muzzle brake has a large open forward end  52  and conical chamber  50 , the baffles  80  may include an elongated conical shape that takes advantage of and extend into this open area at the front of the brake  10 . 
         [0032]    Accordingly, the present invention provides a relatively low cost unit that can be attached with ease and modularity to a Krinkov-type muzzle brake. As discussed above, the sale, possession and use of muzzle brakes is generally not restricted by state and federal laws. The modular noise suppressor, which is subject to registration and a transfer tax through an extended procedure, may be added at a later time. 
         [0033]    When the suppressor unit  70  assembled onto the muzzle brake  10 , the open forward end  52  of the conical chamber  50  is enclosed. In this configuration, the conical forward portion  24  of the inner body member  22  becomes a baffle and the inner chamber  30  and conical chamber  50  of the muzzle brake device  10  become baffle chambers contributing to the overall noise suppression effect of the assembled unit. 
         [0034]    While one embodiment of the present invention has been described in detail, it should be apparent that modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention. Therefore, the foregoing is intended only to be illustrative of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not intended to limit the invention to the exact construction and operation shown and described. Accordingly, all suitable modifications and equivalents may be included and considered to fall within the scope of the invention, defined by the following claim or claims.

Technology Classification (CPC): 5