Abstract:
Firing pins and breechblocks for firearms are disclosed. An example firing pin includes an elongated, generally cylindrical firing pin shaft. The shaft has at least one thickened guide section. The firing pin also includes a non-tapered end having a point. The non-tapered end comprises at least a portion of one of the at least one guide sections.

Description:
RELATED APPLICATION  
       [0001]     This patent arises from a continuation of International Patent Application Serial No. PCT/EP2003/007795, filed on Jul. 17, 2003, and which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE DISCLOSURE  
       [0002]     This disclosure relates generally to firearms, and, more particularly to firing pins and breechblocks for firearms.  
       BACKGROUND  
       [0003]     Prior art firing pins similar to those disclosed herein are known from German Patent DE 570 920 C, German Patent DE 3 00 692 C, U.S. Pat. No. 2,842,885 and U.S. Pat. No. 2,425,434.  
         [0004]     In the prior art, the firing pin of, for example, a machine gun, penetrates a bore in the breechblock and/or the bolt of the breech mechanism. When the gun is fired, the firing pin is intended to strike the priming cap of the cartridge so powerfully that the cartridge is reliably fired.  
         [0005]     In the past, the firing pin has usually been designed such that it tapers to the front and ends in a very slim point (e.g., the tapered point may be in the shape of a bottle or may be conical). The slim point penetrates a bore in the breechblock with slight clearance. Due to the small diameter of the point, a high surface pressure is obtained on the priming cap at the position at which the point strikes the cap. Consequently, even in the case of a very slight impact on the firing pin, one can expect reliable firing. Moreover, due to the small diameter of the bore in the breechblock, so-called primer failures are prevented, or at least made as rare as possible. In some cases the copper, tombac or brass plate of the cap bursts open during the shot, so that gas escapes to the rear into the breech mechanism. Furthermore, the sheet metal of the cap can lodge between the firing pin and the edge of the bore in the breechblock. This lodging of the sheet metal of the cap can result in jamming of at least the firing pin.  
         [0006]     Primer failures occurred frequently at the end of the 19 th  century when the first center fire cartridges were employed. At that time, people had little experience with the selection of cap sheet metal. In war productions in the case of cartridges with Berdan caps, the primer bores in the cartridges were sometimes larger than necessary. Today, particularly with Boxer caps, there is hardly any reason to fear primer failures due to primer bores that are too large. The danger of primer failures, however, continues to exist. For example, the danger of such failures may arise when, for example, in a time of war, the production of cartridges is accelerated by the lifting of production inspections, when it becomes necessary to use replacement materials for cap sheet metal, and/or when the possibility of sabotage in the production of cartridges arises (for example, no primer bore).  
         [0007]     Another reason for the tapered end structure of the above-described, known firing pins is the fact that such a firing pin, which is tapered or offset to the front, usually cannot protrude from the front of the bore to cause breakdowns in reloading. Of course, this holds true only for an undamaged firing pin.  
         [0008]     However, the price to be paid for this advantage includes: (a) an offset or tapered and, thus, difficult to manufacture, bore in the breech mechanism or bolt, (b) difficulties in firing when an air cushion forms under the recess, and (c) difficulties in hardening of the firing pin, which tends to break off precisely at the root of the slim point. This danger of breaking is increased by the fact that, for example, in the case of a machine gun, after a long series of shots the firing pin becomes quite hot. Moreover, such a bore is difficult to clean.  
         [0009]     In submachine guns (such as, for example, the Soviet PPSh 41), the firing pin has been replaced by a short pin with a triangular cross section. As a result of the triangular shape of the pin, the air cushion effect cannot occur. Moreover, each weapon is supplemented with a replacement firing pin, so that a broken or bent firing pin can be rapidly replaced in emergencies. However, the shooter does not benefit much from this feature if the breakdown happens during battle. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a schematic cross-sectional view of the front portion of a breechblock/bolt for a conventional machine gun,  
         [0011]      FIG. 2  illustrates an example firing pin constructed in accordance with the teachings of the invention.  
         [0012]      FIG. 3  shows the example firing pin of  FIG. 2  located in an example breechblock. 
     
    
     DETAILED DESCRIPTION  
       [0013]      FIG. 1  is a schematic, longitudinal cross-sectional view of a conventional breechblock  1  of a machine gun. This breechblock  1  has a median axis  21 , which is aligned with the axis of the bore of the weapon. The axis  21  is located at the center of the bolt  3 . The bolt  3  is structured to hold the bottom of a cartridge. Further a central bore  5  for holding and guiding a firing pin  7  is provided. The bore  5  terminates in the breechblock  1 . The forward (i.e., distal) end of the bore  5  has a narrowing  9 , which can only be manufactured with great effort and expense. In particular, it is difficult to manufacture a bore  5  with a narrowing  9  having a good surface finish.  
         [0014]     A firing pin  7  is movably disposed in the bore  5 . This firing pin  7  has a tapered, slim point  11 . The slim point  11  is dimensioned in such a way that it penetrates the narrowing  9  of the bore  5  and can protrude out of it a distance when the firing pin  7  is in its foremost position.  
         [0015]     During firing the slim point  11  strikes the priming cap of the cartridge and ignites it. If one fires the weapon without a cartridge in the chamber, then the forward movement of the firing pin  7  is stopped by a stop and/or a compressed spring located near the rear of the firing pin  7  (i.e., in the area to the left in  FIG. 1 ). Such a stop/spring must be structured with sufficient tolerance such that the machine gun fires reliably every time, even in the case of a replacement firing pin  7  which is manufactured a long time after the manufacturing of the machine gun. In the case of unfavorable tolerances, when the weapon is fired without a cartridge in the chamber, the transition of the firing pin  7  (i.e., the area between the shaft and the slim point  11 ) will strike the narrowing  9  of the bore  5 . As a result, there is a possibility that the firing pin  7  could break in these circumstances.  
         [0016]     To address this issue, the slim tip  11  is made longer than absolutely necessary. As a result, there is the risk that vibrations could occur during impact, which could also cause the firing pin to break.  
         [0017]     An example firing pin  17  constructed in accordance with the teachings of the invention is shown in  FIG. 2 . The scale of reproduction in  FIG. 2  is smaller than that employed in  FIG. 1 . The firing pin  17  of  FIG. 2  is cylindrical over the greater part of its length and has slightly laterally projecting guide sections  13  which guide it in its bore. The rear end of the pin  17  has a thickening  15 , which forms a stop. If necessary or desired, the thickening  15  can cooperate with a firing pin spring.  
         [0018]     Unlike the prior art firing pins described above, the front end of the firing pin  17  is not offset, tapered or slim. Instead, the firing pin  17  of  FIG. 2  is equipped with a plain, non-tapered, point  19 , which achieves reliable firing of the priming cap of a cartridge. Preferably, the point  19  is integral with, and forms the end of, a guide section  13 .  
         [0019]     As a result of this structure, the firing pin  17  does not require a tapered bore  5 , but instead can be used with a non-tapered, continuous cylindrical bore. In other words, the pin  17  may be used with a bore which exhibits no narrowing  9  or tapering whatsoever. Such a bore may be manufactured cheaply, quickly, and with high precision, since it can be finished to gauge easily by means of re-reaming.  
         [0020]     The length of the illustrated firing pin  17  is about 85 mm. The diameter of the illustrated firing pin  17  in the areas of the guide sections  13  is about 3 mm. This measure is 2 or 3 times larger than that of conventional firing pins. There is no need to fear the formation of an air cushion, since any oil residues from the firing pin  17  are forced out of its bore. The same holds true for any dirt that could possibly penetrate the bore, since there is no narrowing  9  at which dirt can gather.  
         [0021]      FIG. 3  illustrates the firing pin  17  of  FIG. 2  disposed in a breechblock/bolt with a substantially cylindrical bore.  
         [0022]     From the foregoing, persons of ordinary skill in the art will appreciate that the above disclosed firing pin  17  is substantially unbreakable, even though it may have considerable length. Additionally, a breechblock/bolt with a simplified bore is also achieved.  
         [0023]     As described above, the end of the firing pin  17  is a generally cylindrical, non-tapered section that terminates in a plain point  19 , which is directly joined to the non-tapered end. The non-tapered end is directly joined to the cylindrical shaft of the pin  17 . The previously available, slim point  11 , which is usually offset (e.g., tapered) relative to the shaft of the firing pin, is discarded.  
         [0024]     In retrospect, the established practice in the prior art teaches away from the non-tapered point structure disclosed herein because persons of ordinary skill in the art were afraid of the danger of a primer failure due to the greater contact surface of the point with the cap in the context of a non-tapered tip. Further, in the case of a primer failure, too great of a surface on the firing pin was thought to be disadvantageous.  
         [0025]     However, experiments with the firing pin  17  disclosed herein have proven the opposite. Specifically, the firing pin  17  penetrates less deeply and with a much greater radius into the priming cap than prior art firing pins. As a result, there are significantly fewer primer failures, even if the sheet metal of the cap is defective or damaged.  
         [0026]     However, if the cap does blow out, (for example, due to a lack of a primer vent hole in the cartridge), then the load of the cap is significantly lower as a result.  
         [0027]     Further, by using the firing pin  17  disclosed herein, the risk of breaking off the slim point of a prior art firing pin is eliminated, because the firing pin  17  has no such slim point. In the case of high temperatures, there is also no heat build-up in the point of the firing pin  17 . In the case of overloaded cartridges, the return of the cap does not cause any breakdowns.  
         [0028]     The firing pin  17  disclosed herein is well suited for use with a shooting breech principle wherein the breech mechanism is caught in the rear position after a shot is fired, since, in such circumstances, the firing pin  17  forms one unit with the breech mechanism and the entire breech mechanism mass plus the breech-closing spring can act on the primer during firing.  
         [0029]     While in the prior art, the broken off, slim point of the firing pin could wedge and possibly unintentionally trigger a shot, this danger no longer exists.  
         [0030]     The firing pins  17  and the associated bore in the breech mechanism disclosed herein are simpler and cheaper to manufacture then prior art pins and mechanisms. Moreover, in contrast to the prior art, the risk of an air cushion buffering the firing pin  17  in the case of an oiled up bore does not exist.  
         [0031]     Moreover, the fact that a fouling of a narrowed bore is no longer possible (because the bore is not narrowed or tapered), and the fact that cleaning the cylindrical bore is possible (e.g., by means of a wick or a thick pipe cleaner) without further difficulties, are of particular importance.  
         [0032]     Persons of ordinary skill in the art will appreciate that the example firing pin  17  disclosed herein is much more mechanically and thermally stable than the known firing pin shown in  FIG. 1 . As a result, the example firing pin  17  of  FIGS. 2 and 3  has, on average, a significantly longer service life. Such persons will also appreciate that the manufacturing of the firing pin  17  and its associated guide bore is simpler and cheaper then the prior art counterparts. Breakdowns caused by fouling and ammunition defects practically no longer have an effect when the example firing pin  17  of  FIG. 2  is employed.  
         [0033]     As is known, to even further improve the precise manufacturing and the protection from fouling, at least one slightly thickened guide section  13  is arranged along the shaft. The guide section  13  acts as a support against transverse vibrations and as a piston ring which ensures a cleaning of the bore.  
         [0034]     It is preferable that the simple point  19  of the firing pin  17  forms an end of one of the guide sections  13  (i.e., one of the guide sections  13  is located at the end of the firing pin  17 ). As a result, the point  19  has the greatest possible radius. On the other hand, the presence of thickened guide sections  13 , as opposed to a continuously thickened shaft, ensures the shaft is not too thick and, thus, the firing pin  17  is not too heavy. This results in weight reduction and more rapid firing.  
         [0035]     The following measurements have proven to be particularly expedient. The length of the shaft may be about 60 to 100 mm, but, 75 to 85 mm is better, and approximately 80 mm is believed to be best of all. The diameter of the shaft at the thickening(s)  13  is approximately 3 mm. The diameter of the point  19  is approximately the same as the diameter of the priming cap. However, if necessary the diameter of the point  19  may be reduced by the sheet thickness of the cylindrical priming cap border and the tolerances for the concentric arrangement of the cartridge and breech mechanism bore.  
         [0036]     Although certain example methods and apparatus have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.