Abstract:
An improved muzzle-loading firearm which is achieved by modifying the design of the breech plug to include a replaceable aperture adjacent to the firing chamber which can be easily replaced if damaged beyond repair. In the preferred embodiment, the breech plug is adapted to receive an ejectable firing module which permits loading of the firearm as a muzzle-loader, while also permitting the firing module to be inserted and ejected like a cartridge in a conventional breech loading firearm.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. Ser. No. 08/886,296, filed Jul. 1, 1997, now U.S. Pat. No. 5,860,240, issued Jan. 19, 1999, which, in turn is a divisional of U.S. Ser. No. 08/630,693, filed Apr. 12, 1996, now U.S. Pat. No. 5,642,583, issued Jul. 1, 1997, which, in turn is a divisional of U.S. Ser. No. 08/317,210, filed Oct. 3, 1994, now U.S. Pat. No. 5,511,334, issued Apr. 30, 1996. 
    
    
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates generally to firearms and, more particularly, to an improved breech plug for a muzzle-loading firearm. 
     (2) Description of the Prior Art 
     Modern breech-loading firearms, such as rifles, include a barrel having an axial bore, a stock to support the barrel, and a receiver at the breech end of the barrel. The receiver is comprised of a housing which includes a chamber for insertion of a cartridge into the breech of the barrel, a means for firmly securing the cartridge in the breech of the barrel in a sealed and locked position, a firing pin to discharge the cartridge primer, a trigger to move the firing pin into engagement with the cartridge primer, and an ejector to remove the cartridge after firing. 
     Muzzle-loading rifles and other muzzle-loading firearms are also comprised of a barrel with an axial bore and a supporting stock. However, a muzzle-loading rifle is loaded by inserting a charge of powder, wadding and shot through the muzzle end of the barrel and tamping the charge securely into the breech end of the barrel. The powder is then ignited, e.g., by striking a percussion cap, which sends a flame, normally through a small opening or flame bore, into the breech of the barrel through a breech plug which separates the primer from the powder charge. 
     Muzzle-loading rifles have several disadvantages in comparison with breech-loading cartridge rifles. They are more difficult and time consuming to load, and require greater skill to use. Malfunctions are more common due to the relatively more complex firing mechanisms required to ignite the powder. Muzzle-loading rifles are effected by inclement weather, particularly rain and moisture which affects the powder and causes the rifle to misfire. Muzzle-loading rifles must also be cleaned thoroughly to prevent clogging and corrosion by the powder residue. 
     Despite these disadvantages, many hunters and firearms enthusiasts prefer to use muzzle-loading firearms, at least on some occasions, due to the nostalgia and the sport which the muzzle-loaders afford. In addition, many states allow a longer hunting season and special hunting areas for muzzle-loading firearms, due to the greater challenge provided and, consequently, the much smaller number of animals taken. 
     Various designs have been proposed for the construction of improved muzzle-loading rifles. For example, U.S. Pat. No. 4,700,499 to Knight discloses a muzzle loading rifle that uses a “nut cracker” type of action to fire a conventional percussion cap. 
     U.S. Pat. No. 3,780,464 to Anderson and U.S. Pat. No. 4,283,874 to Vaughan disclose mechanisms for replacing the flash hole structure in breech or muzzle loading firearms to allow firing with modern metallic cartridge primers. Both inventions use a cap covering to hold the primer in place until firing. 
     U.S. Pat. Nos. 4,227,330 and 4,232,468 to Chapin disclose a conversion plug that can be configured to be removably inserted into the breech of a breech loading firearm to convert the firearm into a muzzle loading type. The conversion plug includes a primer cap receiving chamber which communicates with the bore of the rifle through a flash hole. 
     U.S. Pat. Nos. 4,222,191 to Lee et al; U.S. Pat. No 4,437,249 to Brown et al; and U.S. Pat. No 5,010,677 to Carron all disclose variations of the Chapin type of conversion plug for converting a shotgun or rifle into a muzzle loader. 
     U.S. Pat. Nos. 5,511,334 and 5,642,583, issued to Ball et al., disclose a way to convert a modern breech lock, cartridge rifle into a rifle that can be used as a muzzle-loading rifle. The disclose of these patents are hereby incorporated by reference in their entirety. However, even in this design the flame bore extending through the breech plug can become clogged or corroded after repeated use. This may require that the entire breech plug be replaced at some expense. 
     Thus, there remains a need for a new and improved breech plug for a muzzle-loading rifle which can be more easily cleaned after use while, at the same time, utilizes a replaceable aperture adjacent to the firing chamber which can be easily replaced if damaged beyond repair. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an improved muzzle-loading firearm which is achieved by modifying the design of the breech plug to include a replaceable aperture adjacent to the firing chamber which can be easily replaced if damaged beyond repair. In the preferred embodiment, the breech plug is adapted to receive an ejectable firing module, such as disclosed in the above-referenced Ball patents which permits loading of the firearm as a muzzle-loader, while also permitting the firing module to be inserted and ejected like a cartridge in a conventional breech loading firearm. 
     Thus, in the preferred embodiment, the muzzle-loading rifle of the present invention is comprised of a barrel into which powder, wadding and ball are loaded through the muzzle or discharge end in a conventional manner, a breech loading receiver attached to the breech or rear end of the barrel, and a breech plug within the breech end of the barrel adapted to receive a firing module having the shape of a conventional cartridge wherein the breech plug includes a replaceable aperture. 
     The receiver of the present invention may be of a variety of designs used in modern rifles, and may be a bolt action, a lever action, a rolling block or a semi-automatic design. In either case, the receiver will be comprised of a housing, a firing mechanism movable between an open position and a closed and firing position, a firing pin, a firing mechanism to strike the firing pin, and an ejector designed to eject a spent cartridge after firing. The housing may be threaded to attach a barrel. 
     The barrel may have external annular threads at its breech end for attachment to the receiver housing. In accordance with the present invention, the barrel is drilled and tapped at its breech end to form internal plug engaging threads to secure the breech plug. 
     The breech plug is comprised of a cylindrical rear section and an axially aligned and integral, cylindrical front section. The rear section, which is preferably of a larger diameter than the barrel bore, is externally threaded to engage the internal threads of the barrel bore. The front section has an external diameter equal to the internal diameter of the barrel bore, and is adapted to snugly fit within the barrel bore when the breech plug is threaded into the barrel breech. At least a portion of the flame bore adjacent to the firing chamber includes a replaceable aperture which can be removed for cleaning or replaced if damaged beyond repair. The rear face of the breech plug is perpendicular to the axis of the plug. The breech plug shape may also be modified to accommodate the particular configuration of the firearm being modified. For example, the face of the plug may need to be configured to receive the cartridge ejector. 
     In the preferred embodiment, a cylindrical firing module receiving chamber, axially aligned with the barrel bore, extends from the rear face of the breech plug. The firing module receiving chamber is formed of a continuous interior cylindrical wall, terminating in a tapered or conical inner face, which tapers inwardly to mate with a firing module. The length of the chamber is sufficient to accommodate the firing module, with only the ejection rim of the module extending from the chamber. The flame bore is axially aligned with the firing module receiving plug and extends between and communicates with the firing module receiving plug and the barrel bore, providing a passageway for a flame to travel from the firing module within the chamber to the barrel bore, and thus ignite powder within the breech of the barrel. In the preferred embodiment, the flame bore tapers radially outwardly at its forward end to form a powder receiving chamber. 
     The firing module itself is preferably comprised of a thick cylindrical wall surrounding a central, axially aligned flame bore having a uniform diameter. The firing module terminates at its rear end in a vertical rear face, and is tapered at its forward end to engage the tapered inner face of the firing module receiving plug. An annular shoulder extends around the periphery of the firing module proximate to the module&#39;s rear face to create a radial ejection flange or rim adjacent the rear face of the firing module. The overall length of the module will depend on the design of the particular firearm. An igniter receiving chamber is recessed into the rear face of the firing module and is axially aligned with the flame bore. The chamber is of a shape and dimension such that it will snugly hold a commercially available igniter, such as a primer cap or a percussion cap. An igniter is fitted snugly into the chamber. 
     Accordingly, one aspect of the present invention is to provide a muzzle-loading firearm including: (a) a breech loading receiver including a firing mechanism movable between an open position and a firing position; (b) a barrel having a breech end engaging said receiver and a bore extending from said breech end for receiving a powder charge; and (c) a breech plug within the breech of said barrel having a breech end aligned with the breech end of said barrel and a barrel bore end aligned with the bore end of said barrel, said breech plug further including: (i) an igniter receiver positioned at the breech end of said breech plug; (ii) a flame bore extending from said igniter receiver to the barrel bore end of said breech plug; and (iii) a replaceable aperture at the barrel bore end of said flame bore, said aperture being aligned with said flame bore to allow a flame front to be distributed to a powder charge. 
     Another aspect of the present invention is to provide a breech plug for use in a muzzle-loading firearm, said breech plug including: (a) an igniter receiver positioned at the breech end of said breech plug; (b) a flame bore extending from said igniter receiver to the barrel bore end of said breech plug; and (c) a threaded plug positioned at said barrel bore end of said breech plug, said threaded plug including an aperture aligned with said flame bore to allow a flame front to be distributed to a powder charge. 
     Still another aspect of the present invention is to provide a muzzle-loading firearm including: (a) a breech loading receiver including a firing mechanism movable between an open position and a firing position; (b) a barrel having a breech end engaging said receiver and a bore extending from said breech end for receiving a powder charge; and (c) a breech plug within the breech of said barrel having a breech end aligned with the breech end of said barrel and a barrel bore end aligned with the bore end of said barrel, said breech plug further. including: (i) an igniter receiver positioned at the breech end of said breech plug; (ii) a flame bore extending from said igniter receiver to the barrel bore end of said breech plug; (iii) a threaded plug positioned at said barrel bore end of said breech plug, said threaded plug including an aperture aligned with said flame bore to allow a flame front to be distributed to a powder charge; and (iv) a firing module receiving chamber for receiving a firing module. 
    
    
     These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a muzzle-loading rifle including a breech plug constructed in accordance with the present invention loaded with a preferred firing module in firing position; 
     FIG. 2 is a perspective view of the preferred firing module; 
     FIG. 3 is a cross-sectional view of an alternative embodiment of the firing module using a percussion cap as the igniter; 
     FIG. 4 is a perspective view of the alternative firing module shown in FIG. 3 with the percussion cap removed; 
     FIG. 5 is an end view of the breech plug taken along line  5 — 5  in FIG. 1; 
     FIG. 6 is an end view of the breech plug taken along line  6 — 6  in FIG. 1; and 
     FIG. 7 is a cross-sectional view of a muzzle-loading rifle including an alternative embodiment of the breech plug constructed in accordance with the present invention loaded with a preferred firing module in firing position, wherein the threaded plug extends the entire length of the flame bore. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description, like reference characters designate like or corresponding parts throughout the several views. Also in the following description, it is to be understood that such terms as “forward,” “rearward,” “left,” “right,” “upwardly,” “downwardly,” and the like are words of convenience and are not to be construed as limiting terms. 
     Referring now to the drawings in general and FIG. 1 in particular, it will be understood that the illustrations are for the purpose of describing a preferred embodiment of the invention and are not intended to limit the invention thereto. As best seen in FIG. 1, there is shown a muzzle-loading firearm, generally designated  10 , showing part of a receiver  12  and a barrel  14  of a conventional bolt action rifle which has been modified for muzzle-loading by plugging the breech of barrel  14  with a breech plug  16  adapted to receive a firing module  18  shown inserted into breech plug  16 . 
     Barrel  14  includes a central axial bore  20  which extends from the breech end of barrel  14  to the muzzle or discharge end of the rifle. The breech end of barrel  14  is internally threaded with threads  22  to receive breech plug  16 , which is externally threaded along a rear section with threads  24  which engage threads  22 . The exterior surface of the breech end of barrel  14  is also threaded with threads  26  to engage an internally threaded opening  28  in receiver housing  30 . 
     Receiver housing  30  also includes a bolt bore  32  axially aligned with barrel bore  20  to slidably receive a bolt  34  which is moveable between an open position and a closed and locked position. Bolt  34  includes a bolt face  36  and an axial bore  38  which slidably receives a firing pin  40 . An ejector  42  is positioned in front of bolt  34 . 
     The breech plug  16  is comprised of a central, axially aligned, firing module receiving recess or chamber  44  formed of a cylindrical side wall  46  and an inwardly tapered front wall  48 . Wall  48  is tapered to provide a larger surface for engagement with the forward end of firing module  18 , thus producing a better seal. A central, axially aligned flame bore  50  extends from the center of front wall  48  to barrel bore  20 , and terminates in an outwardly tapered front wall  52 . The front section of plug  16  is threaded into barrel  14 . The face of plug  16  that is adjacent the bolt and firing pin when inserted into the firearm, as best seen in FIG. 5, includes a radial slot  54  to facilitate insertion and removal of plug  16  into barrel  14 , and an ejector receiving slot  56 , which allows ejector  42  to engage firing module  18  for extraction. 
     A central, axially aligned passageway extends between the ignition chamber and barrel bore to provide for the spark to travel from the ignition chamber to the powder. The passageway includes a flame bore  50  and an outwardly tapered front wall  52 . The front, barrel bore end of the flame bore  50  includes a threaded plug  100  having an aperture  102  that aligns with the flame bore. In the preferred embodiment, the diameter of the aperture  102  is about equal to the diameter of the flame bore  50 . The threaded plug  100  has external threads  104  which mate with internal threads  106  on the interior of the breech plug. A tool cavity  80  for receiving a tool for installation or removal of the threaded plug is positioned at the front end of the threaded plug  100 . As best seen in FIG. 6, the preferred embodiment of the present invention includes a tool cavity  80  sized for insertion of an Allen wrench. The opposite end of the plug may include fins, similar to a star lock washer, to help prevent the plug from working loose. 
     The threaded plug  100  with aperture  102  is designed and used to preserve the integrity of the front, barrel bore end of flame bore  50  diameter. After substantial firings, the aperture  102  may wear and become larger thereby reducing the possibility of ignition of the powder because of excessive disbursement of the spark. Routine maintenance in which the threaded plug  100  is replaced insures the integrity of the flame bore and proper disbursement of the spark for ignition. The threaded plug illustrated in FIG. 1 extends only a portion of the flame bore  50  where most damage occurs. However, it is understood that this invention contemplates a threaded plug having any length up to the full length of the flame bore. 
     The preferred firing module, shown in FIGS. 1 and 2, is comprised of a thick cylindrical wall  58  around a central, axially aligned, flame bore  60 . An axially aligned igniter recess or chamber  62  extends inwardly from the breech end of firing module  18 . Flame bore  60  extends from the inner face of igniter chamber  62  to flame bore  50  in plug  16 , to form a flame passageway from igniter chamber  62  to barrel bore  20 . Igniter chamber  62  is sized to snugly receive a primer cap  64 , such as a conventional shotgun primer cap, and includes an annular shoulder to receive the annular rim of cap  64 , so that the face of cap  64  is flush with the face of firing module  18 . An annular shoulder  66  extends around firing module  18  to form a radial ejector flange  68 . 
     An alternative embodiment of a firing module  90  is shown in FIGS. 3 and 4. This alternative module differs from the preferred firing module  18  in that the igniter chamber is comprised of an annular shoulder  72 , which is adapted to receive a conventional, low pressure percussion cap  74 , such as is normally used in black powder firearms. This type of firing module is for use by hunters in areas where the law may require the use of low pressure percussion only. 
     In operation, the rifle is first loaded by inserted powder, wadding and shot into bore  20 . The powder is tamped into the flared end  52  of flame bore  50 . Then, for safety, firing module  18  is chambered into chamber  44  of plug  16  and bolt  34  is moved to the forward closed and locked position with bolt face  36  tightly in engagement with the rear face of firing module  18 . The rifle is then fired in a conventional manner, e.g., by pulling a trigger, not shown, to bring the end of firing pin  40  into engagement with primer cap  64 , producing a flame which travels through flames bores  60 ,  50 , and  52  to ignite the powder in bore  20 , thereby propelling the bullet or shot from barrel  14 . Spent firing module  18  is then ejected in the same manner as one would remove a spent cartridge from a modern breech loading cartridge rifle by withdrawing bolt  34  to open the receiver chamber and withdrawing firing module  18  from chamber  46  with ejector  42 , which engages firing module  18  by moving into shoulder  66  and then moving rearwardly, pushing against ejector rim or flange  68 . Module  90  can be used instead of module  18 , and is fired and ejected in the same manner. 
     Periodic maintenance may include removing the breech plug  16  from the breech of the barrel  14 , such as by inserting a screw driver between radial slots  54 . The threaded plug  100  may be removed from the front, barrel bore end of the flame bore  50  by inserting a tool such as an Allen wrench into the tool cavity. A replacement threaded plug  100  may then be inserted to maintain the flame bore  50  and ensure adequate spark distribution to the powder. The breech plug  16  may then be replaced into the barrel  14 . 
     Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. While the firearm of the present invention has been described in terms of the modification of an existing rifle, the invention is also applicable to other breech loading, locking firearms, such as muzzle-loading handguns and shotguns. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the follow claims.