Abstract:
A firing nipple for a muzzle loading firearm where there are provided a plurality of exterior wall sections of differing diameters to provide abutment shoulders to sealingly engage against surfaces on a breech plug, and an internal chamber having a tapering wall to direct the hot gasses. The arrangement substantially prevents blow back and provides for an increased efficiency in the firing of a weapon.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the general field of firearms and is particularly concerned with a firing nipple for muzzle loading firearm. 
     BACKGROUND OF THE INVENTION 
     Muzzle loading firearms which were once considered the ultimate weapon have been used increasingly in recent years both in tournaments and for hunting. Indeed, in some regions regulations allow for a extended hunting season for users of muzzle loading firearms since such their use allows the game to escape more easily. 
     Most muzzle loading firearms now use a so-called percussion type firing system instead of the so-called flintlock method which was prevalent up until the 19 th  century. Conventional percussion type firing systems including a percussive firing cap and a nipple communicating with the firearm ignition chamber. 
     Conventional percussion caps are typically made out of a thin soft metal formed into a substantially cap shape. The percussion cap is provided with a relatively thin coating of priming compound on the inside of its flat surface of the closed portion of the cap. For the priming compound to ignite it must be compressed between two surfaces. During use, the percussion cap is placed on the nipple so that when the hammer strikes the cap the priming compound is compressed between the hammer and the nipple which thus acts as an anvil. Compression of the priming compound between the hammer and the nipple ignites the priming compound. This produces a predetermined quantity of burning gas in the nipple. The gas in the nipple is forced under considerable pressure into the ignition chamber of the firearm igniting the propellant charge therein. The firing cap naturally needs to fit snugly over the nipple in a position to be struck by the firearm&#39;s hammer. 
     The ignition assembly of most percussion type muzzle loading firearms further includes a breech plug mounted within the breech of the firearm. Typically the breech plug is screwed into the breech. The breech plug may be provided with a threaded nipple bore for threadably receiving the firing nipple. 
     Heretofore, nipples usable in conjunction with percussion caps to ignite the propellant charge in a firearm have included an elongated body having a passage extending longitudinally therethrough. Such passage generally includes a cylindrical primary chamber communicating with the cap receiving end of the nipple. This primary chamber serves as an explosion chamber for the percussion cap. The passage also includes a relatively small bore constriction chamber communicating with the gas discharge end of the nipple. This constriction chamber serves to restrict flow of particles out of the primary chamber whereby a high gas pressure within the primary chamber occurs at the time of the percussion explosion. 
     The prior art discloses various modifications of firing nipples. However, prior art constructions suffer from at least one major drawback. Indeed, misfiring of muzzle loading firearms utilizing a percussion cap and a percussion nipple has proven to be a common problem. The chance of misfiring would be lessened considerably by using a more powerful percussion or potent percussion cap. However, the use of a more powerful percussion cap would increase the risk of so-called blow back of the discharge from the percussion cap. Blow back occurs when the heated gases from the detonated firing cap blow back in the direction of the cap. It can be easily understood that such blow back adversely affect ignition efficiency and may even potentially present a danger to the firearm user. Such blow back effect may also occur from heated gases upon ignition of the propellant charge within the firearm ignition chamber, again diminishing the firearm performance and creating potential danger to the firearm user. 
     In order to reduce the amount of misfiring, improved firing caps have been developed. For example, the so-called 209 type of fire cap has proven to be more reliable. 
     Accordingly, there exists a need for an improved firing nipple for muzzle loading firearms. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, there is provided a firing nipple for a muzzle loading firearm comprising a body portion having an inlet end and an outlet end, an exterior wall comprised of a first exterior wall section, a second exterior wall section and a third exterior wall section, the first exterior wall section being situated proximate the inlet end, the third exterior wall section being situated proximate the outlet end and the second exterior wall section being situated intermediate the first and third exterior wall sections, the first exterior wall section having a greater diameter than a diameter of the second exterior wall section to thereby form a first exterior abutment shoulder therebetween, 
     the second exterior wall section diameter being greater than a diameter of the third exterior wall section to thereby form a second exterior abutment shoulder therebetween, an interior wall comprised of a first interior wall section, a second interior wall section and a third interior wall section, the first interior wall section being situated proximate the inlet end and defining a first chamber, the third interior wall section being situated proximate the outlet end and defining a third chamber, and the second interior wall section being located between the first interior wall section and the third interior wall section and defining a second chamber, the second interior wall section having an interior diameter less than a diameter of the first interior wall section to thereby form a first interior abutment shoulder therebetween, the second interior wall section interior diameter being less than a diameter of the third interior wall section, and an inwardly tapering wall section extending between the second interior wall section and the third interior wall section. 
     Advantages of the present invention include that the proposed firing nipple is specifically adapted to be used with relatively high performance percussion caps in muzzle loading firearms thus reducing the risks of misfiring. 
     The proposed firing nipple is specifically configured so as to provide easy and stable mounting of the percussion cap thereon. The firing nipple is provided with a built-in means for ensuring stable and safe support of the percussion cap. 
     The configuration of the passage formed in the firing nipple is optimized to increase the igniting capacity of the percussion cap. Furthermore, the firing nipple is provided with built-in means for reducing the risk of blow back both from the percussion cap and the propellant charge in the firearm. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view illustrating a firing nipple for muzzle loading firearms in accordance with an embodiment of the present invention; 
     FIG. 2 is an end view of the firing nipple shown in FIG. 1 as seen from the left hand side thereof; 
     FIG. 3 is a top view of the firing nipple shown in FIG. 1; 
     FIG. 4 is a side view of the firing nipple shown in FIG. 1; 
     FIG. 5 is a longitudinal cross sectional view of the firing nipple shown in FIG. 1; 
     FIG. 6 is a partial longitudinal cross sectional view illustrating the firing nipple of FIG. 1 threadably mounted to a breech plug, the breech plug being screwed into the breech of a firearm; and 
     FIG. 7 is a partial longitudinal cross section of a conventional breech plug. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to FIG. 6, there is shown a portion of a firearm employing a percussion cap firing system for igniting a propellant charge within the firearm. The percussion cap firing system includes a nipple  10  in accordance with one embodiment of the present invention and which is adapted to be threadably mounted to a breech plug  12 . Breech plug  12  is, in turn, threadably mounted to the barrel  14  of a firearm. The barrel  14  is typically made out of a single piece of cast and machined steel defining a breech  16  therein. The rearward section of the breech  16  adjacent the breech plug  12  defines a powder chamber section  18  for receiving a propellant charge such as a gun powder  20  packed thereinto. 
     Referring now to FIGS. 1 to  5 , there is shown in greater detail the configuration of the nipple  10 . The nipple  10  has a generally elongated body defining a first or proximal end  22  and a longitudinally opposed second or distal end  24 . The nipple  10  is provided with a longitudinal channel extending therethrough and which will be discussed in greater detail hereinbelow. 
     The external opposed longitudinal ends  22 ,  24  respectively have corresponding planer faces  26  and  28  which occupy substantially parallel geometrical planes. The nipple  10  defines a proximal annular rim section  30  intercepting the face  26 . The annular rim section  30  is provided with two notches  32  formed radially therein. The notches  32  are configured and sized for receiving the blade of a conventional screwdriver or other tool adapted to facilitate rotation of the nipple  10  about its longitudinal axis. 
     The external configuration of the nipple  10  also defines an annular groove  34  positioned adjacent the annular rim section  30 . The annular groove  34  is configured and sized for receiving a biasing means for concentrically biasing the body of the nipple  10  in the region of the groove  34  towards a smaller radius. In a preferred embodiment of the invention, the biasing means takes the form of a wire spring  36 . Both the rim section  30  and the annular groove  34  are provided with a slot  38  intercepting at least a portion thereof. The slot  38  is adapted to slidably receive a locking end section  40  of the spring  36 . 
     The external configuration of the nipple  10  further defines a first exterior wall section  42  and an adjacent second exterior wall section  44 . The first exterior wall section  42  has an external diameter somewhat larger than that of the second exterior wall section  44  so that both the first and second exterior wall sections  42  and  44  define a first exterior abutment shoulder or surface  46  therebetween. As shown in FIG. 6, the first and second exterior wall sections  42  and  44  are configured and sized so that the first abutment shoulder  46  will matingly abut against an exterior shoulder or surface  48  of the breech plug  12 . 
     The external configuration of the nipple  10  still further includes an exterior wall spacing section  50 . The spacing section  50  has an external diameter somewhat smaller than that of the second exterior wall section  44  so that the spacing section  50  and the second exterior wall section  44  together define a second exterior abutment shoulder or surface  52  therebetween. The spacing section  50  and the second exterior wall section  44  are configured and sized so that the second abutment shoulder  52  matingly and sealingly abuts against a breech plug proximal internal shoulder  51 . Also, the external diameter of the spacing section  50  is smaller preventing obstruction or interference. 
     The external configuration of the nipple  10  still further includes a mounting section  58  provided with an external thread  60 . The external thread  60  is adapted to cooperate with the internal thread formed in the internal connecting channel  56  part of the breech plug  12 . The mounting section  58  of the nipple  10  includes an outlet section  62  having an external diameter smaller than the threaded portion of the mounting section  58 . The outlet section  62  and the rest of mounting section  58  thus define yet a third exterior abutment shoulder or surface  64  therebetween. The third exterior abutment shoulder  64  is configured and sized for matingly and sealingly abutting against a second internal shoulder  68  part of the breech plug  12 . The length of the outlet section  62  is preferably sized so that the distal end  24  is positioned substantially adjacent a conically divergent wall  70  which forms part the breech plug  12 . Typically, for Remington type and other firearms a spacing channel  72  extends between the internal threads  56  and the divergent wall  70  of breech plug  12 . Outlet section  62  is thus adapted to extend at least partially through the internal spacing section  72  of the breech plug  12  for reasons which will be hereinafter disclosed. 
     In a preferred embodiment, the external diameter of the rim  30  and the first intermediate section  42  has a value substantially in the range of between 0.425″ and 0.445″, the external diameter of the second intermediate section  44  preferably has a value substantially in the range of between 0.32″ and 0.34″ and the external diameter of both spacing section  50  and outlet section  62  having a value substantially in the range of between 0.2″ and 0.21″. Typically, the nipple  10  has an overall length substantially in the range of between 0.875″ and 0.975″ with the length between the second abutment shoulder  52  and the second end  28  being substantially in the range of between 0.4″ and 0.43″. The length between the first and second abutment shoulders  46  and  52  is preferably substantially in the range of between 0.15″ and 0.17″ with a length between first end  26  and first abutment shoulder  46  being substantially in the range of between 0.33″ and 0.37″ while the annular groove  34  preferably has a thickness in the range of between 0.07″ and 0.09″. 
     Turning now more specifically to FIG. 5, there is shown in greater detail the configuration of an internal longitudinal channel  74 . Channel  74  includes a first large chamber section  76  defined by interior wall  75  and which is configured and sized for receiving an ignition cap. The first chamber section  76  extends into a second chamber  78  defined by interior wall section  79 . An internal shoulder  80  is defined between the first chamber section  76  for abuttingly contacting the distal end of the cap. The second chamber  78  preferably has a generally cylindrical configuration that tapers conically at a distal end thereof into an intermediate section  82 . The cone shaped intermediate section is defined by a conical wall disposed at an angle substantially in the range between 117° and 119° relative to the longitudinal axis of the nipple. The second chamber  78  extends integrally into a smaller diameter third chamber  84  defined by interior wall section  85 . Joined passage sections  82  and  84  define a funnel shaped chamber. 
     In operation, the nipple  10  is threadably attached to the breech plug  12 . The ready the firearm for firing, the propellant charge such a gunpowder  20  is packed into the powder chamber  18  and a percussion cap  78  is slidably introduced into the first chamber section  76 . The cap is releasably attached to the nipple  10  using the spring type component  36  mounted in the annular slot  74  with the locking segment  40  extending through the slot  38 . 
     The cap contains the usual internal explosive charge. A hammer type component, when released by a suitable trigger, strikes the cap exploding its charge. The exploding particles initially extend into the second chamber  78  and are momentarily contained therein under high pressure. The high pressure forces, the heated bases and particles through the tapered conical wall section  82 , into the outlet chamber  84  and thence, into the firing chamber  18 . The heated gases and particles then ignite the propellant charge in the firearm. The sudden rush of hot explosive gases rapidly flowing to or out of the ignition port provide a simultaneous expulsion of the bullet from the gun muzzle. 
     As mentioned previously, the proposed invention is adapted to reduce the risk of blow back. The gas blow back is at least partially related to the fact that at the instant of cap firing, heated gas particles fill the primary chamber creating an intense pressure therein for a brief period. If not quickly released into the main firing chamber the pressurized particles of gas will blow back against the cap. Secondly, following ignition of the firearm propellant charge, a portion of the gasses and particles form that charge are forced back inside the nipple creating further blow back. From the foregoing, it can be appreciated how the present invention in nipple design substantially reduces blow back. Firstly, the first chamber  76  is solidly created with minimal apertures extending threrethrough and is designed so as to reduce the formation of the cap upon ignition of the latter. The only aperture extending through the first chamber  76  retaining the cap consists of the slot  38  used for maintaining the cap within the chamber  76 . 
     The design of the second chamber  78  is also adapted to extend the periods during which the cap combustion products are contained therein. This extended period of time allow more product of ignition to reach the propellant and allows them to achieve the transfer over an extended period of time. The ignition material is thus allowed to reach a higher ignition temperature within the chamber  78  which will, in turn, result in a higher reliability of ignition of the powder  20 . 
     The angular relationship of the cone shaped wall  82  with the longitudinal axis of the nipple  10  allows for a better gas outlet which reduces the risks of blow back within the nipple. This risk is further reduced by the use of a single outlet. 
     The risk of blow back is still further reduced by the use of at least two and preferably three abutment shoulders  46 ,  52  and  64  which sealingly abut against corresponding surfaces of the breech plug  12  for preventing blow back towards the cap  78 . In order to allow for unobstructed abutment of the shoulders  46 ,  52  and  64  against corresponding abutment surfaces of the breech plug  12 , the spacing section  50  is undersized relative to the external diameter of the threaded channel  56  part of the breech plug  12 . Also, the external thread  60  part of the mounting section  58  is given a thread step substantially in the range of 273 to 274 thousands of an inch in order to increase resistance to pressure forces created by the ignition. 
     Furthermore, the outlet section  62  allows the ignition gases to reach directly the divergent cone shaped wall  70  part of the breech plug  12 . Typically, the divergent wall  70  has an angle substantially in the range of 100° relative to the longitudinal axis of the breech  12  plug which allows the ignition gases to reach a wider initial surface of powder  20 . The powder  20  thus ignites more rapidly which, in turn, again reduces the risk of misfiring.