Abstract:
A firing pin safety catch mechanism for a firearm, especially an auto-loading firearm which operates with a closed action such as found on the United States Military&#39;s M16 and its various derivatives. The firearm includes a firing pin which is housed within a bolt carrier group and which is capable of being moved from a rest position in which its proximal end is out of the travel path of the hammer to a firing position. The safety catch mechanism includes a safety catch, a pin and a spring for biasing the safety catch to hold the firing pin in its rest position to prevent the unintentional movement of the firing pin and thereby prevent the unintentional discharge of the host firearm. The safety catch includes a cam surface cooperating with the hammer so that the catch is released from engagement with the firing pin when the hammer has substantially completed its path of travel.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates in general, to firearms, and more particularly, to a spring loaded firing pin safety catch mechanism designed to prevent the unintentional discharge of a firearm. 
     2. Prior Art 
     Numerous firing pin safety devices have been developed and implemented over the years with a varying degree of success. These safety devices have the general purpose of preventing the unintentional discharge of a firearm should the weapon be violently struck from the front (for example, if the firearm accidentally falls on the group causing the muzzle of the weapon to strike a potentially hard surface), or should debris become wedged between the firing pin and its housing causing the firing pin to be stuck in the firing or primed position. 
     Firing pins of the “floating” variety, which do not have any mechanical means preventing the tip from contacting the primer of a cartridge, are common in both the M16 and AK family of firearms. The M16 and its derivates are arguably the most prolific type of firearm in the United States being used by military, law enforcement and civilian shooters. When a hammer strikes the rear end of the firing pin (“front” is understood throughout this document to mean the direction that a discharged projectile would leave the host firearms barrel and “rear” is understood to be opposite of “front”) its energy is transferred to the firing pin which responds by moving forward through the separation distance and striking the primer of the loaded cartridge being held by the barrel&#39;s chamber. 
     Unfortunately, kinetic energy may also be imparted to a floating firing pin unintentionally such as when a weapon is dropped by the user accidentally. Another possibility, when the action of the firearm is released after being drawn fully to the rear, upon seating the firing pin, due to inertia, is still traveling forward only stopping after it strikes the primer of the loaded cartridge. This often leads to a small dimple of the primer&#39;s surface. These provided examples, under the right circumstance, could cause a weapon to accidentally discharge. 
     Devices such as discussed in U.S. Pat. Nos. 2,848,832 &amp; 6,145,234 propose a catch-like safety mechanism mounted to the breech of a firearm. These safety mechanisms rely on a catch which faces the firing pin. The firing pin has a recess proximate its rear end. The recess is located opposite the safety catch or circumferential about the rear end (in the case of U.S. Pat. No. 6,145,234) located opposite the safety catch formed on the safety element. A means to force the safety catch into operational contact with the firing pin recess is provided by both designs. When the safety catch is engaged with the recess, the firing pin is secured and cannot move toward the primer of a cartridge. 
     In the above mentioned safety elements, the safety element are lengthened rearward by a release part having a camming surface. The camming surface of the release parts extends into the travel path of the hammer directly behind the rear of the firing pin. When the hammer strikes the camming surface, and in so doing, forcing the release part, and thus the safety element to the side such that the firing pin is released by the safety catch just prior to the firing pin being struck by the hammer. This results in the firing pin being able to move under the pressure exerted by the hammer resulting in the firearm discharging a round. 
     While the above described safety mechanisms are effective, they are not readily adaptable to the M16 family of weapons. Nothing in these prior art examples would create an operative combination. Further, as example, U.S. Pat. No. 6,145,234 incorporates the extractor element into the leaf spring used in conjunction with the safety catch. There is no way to incorporate such a design into the M16 family of weapons due to the rotational separation of the bolt from the bolt carrier during normal operation. Yet, a need to implement a mechanism which prevents the “floating” movement of the firing pin in the M16 family of weapons and those like it persist. 
     Another weakness with prior art firing pin safeties is that they allow the firing pin a limited range of motion even when held in the rest position. The forward inertia generated when the action is closed coupled with the movement still allowed the firing pin allows the tip of the firing pin to dimple the primer. While it has not been proven that this situation causes out of battery detonation of the loaded cartridge there is evidence that suggest it does. Out of battery detonation occurs when a loaded cartridge is discharged prior to the bolt and cartridge being fully seated in the chamber of the host firearm. 
     It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art. 
     3. Objects and Advantages 
     Accordingly several objects and advantages of the present invention are
         (a) To provide a safety mechanism which prevents the unintentional movement of the firing pin assembly in an auto-loading firearm during manual cycling of the action.   (b) To provide a safety mechanism which may be readily implemented into existing rifle designs.   (c) To provide a safety catch mechanism which may be incorporated into the existing, M16 family of firearms, bolt carrier assembly.   (d) To prevent any unintentional contact between the firing pin and the primer of a cartridge.       

     Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings. 
     SUMMARY 
     The herein disclosed invention consists of a firing pin safety catch mechanism designed for use with a firearm having a separate bolt carrier group and a trigger mechanism. The bolt carrier group includes a bolt carrier and a bolt. The trigger mechanism includes a hammer, firing pin, and a firing spring. The hammer is movable from a cocked position through a path of travel to strike the firing pin. The firing pin spring biases the firing pin into a rest position wherein the tip of the firing pin is not protruding through the face of the bolt. The firing pin has a proximal end and a catch surface, or recess, adjacent the proximal end. The firing pin safety catch mechanism consists of a coil spring, roll pin, and safety catch which are assembled on the bolt carrier. The safety catch is disposed in proximity to the proximal end of the safety catch mechanism and has a first position wherein the safety catch engages the catch surface, or recess, of the firing pin in the rest position and a second position wherein the safety catch disengages with the recess to release the firing pin for movement out of the rest position. The coil spring places force on the distal end of the safety catch mechanism which rotates on the provided roll pin to bias the safety catch into the first position. The safety catch includes a camming surface on the proximal end of the safety catch. Also, the camming surface is disposed within the motion path of the hammer. When the safety catch mechanism is in the first position such that, as the hammer moves from the cocked position through the travel path, the hammer cams the camming surface of the safety catch against the force being applied by the coil spring to move the safety catch from the first position to the second position, allowing the hammer to strike the proximal end of the firing pin thus forcing it forward into the primer of a loaded cartridge. 
     Other features and advantages are inherent in the disclosed apparatus or will become apparent to those skilled in the art from the following detailed description and its accompanying drawings. 
    
    
     
       DRAWINGS 
       The novel features believed to be characteristic of the invention, together with further advantages thereof, will be better understood from the following description considered in connection with the accompanying drawings in which a preferred embodiment of the present invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. 
         FIG. 1  is a side perspective view of my firing pin safety device for auto-loading firearms; 
         FIG. 2  is a longitudinal sectional view of the firing pin safety catch with the firing pin captured by the safety catch and the hammer in a cocked position; 
         FIG. 3  is a similar view to that of  FIG. 2 , but shows the hammer pushing aside the safety catch immediately prior to striking the hammer; 
         FIG. 4  is a similar view to that of  FIG. 2 , but shows the position of the safety catch mechanism and firing pin after the hammer has completed its full path of travel. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings in which like reference characters indicate corresponding elements throughout the several views, as used herein, the word “front” or “forward” corresponds to the end of the bolt carrier assembly where the bolt is located (i.e., to the left as shown in  FIGS. 1  thru  4 ); “rear” or “rearward” or “back” corresponds to the direction opposite the end of the bolt carrier assembly where the bolt is located (i.e., to the right as shown in  FIGS. 1  thru  4 ). The word “proximal” corresponds with the end closest to the shooter, while the word “distal” refers to the end closest to the muzzle of the barrel. The bolt carrier group includes a bolt carrier  30  and a bolt  31 . 
       FIG. 1  illustrates a side perspective view of the preferred embodiment bolt carrier  30  and bolt  31  which has been machined, with a guide groove  15 , to accept the parts comprising the safety catch mechanism  10 . The safety catch mechanism  10  consist of a spring  11 , roll pin  12 , safety catch arm  16 , safety catch  13  and a camming surface  14 . Optionally a, prior art, retaining pin  24  may be used to further prevent the firing pin  20  from falling free of the bolt carrier  30 . 
     The firing pin safety catch mechanism  10  disclosed herein is shown in  FIG. 2  in its&#39; preferred embodiment. The depicted bolt  31  has a recess  33  on its forward area where a loaded cartridge (not shown) rests in the recess  33 . When a trigger (not shown) is operated, the hammer  32  is released from its cocked position to travel through its motion path to a fired position (shown in  FIG. 4 .) resulting in the firing pin  21  protruding through the face of the recess  33  of the bolt  31 . 
     The bolt  31  has a first longitudinal receiving bore  34  formed therein to house the firing pin  20 . A second longitudinal receiving bore  35  is formed in the front or distal end of the bolt carrier  30  to contain the bolt  31 . The firing pin  20  is rearwardly biased into its rest position (shown in  FIG. 2 ) by a firing pin spring  21  mounted between the first longitudinal bore  34  and the firing pin  20  recess  22 . The rest position is defined by the interaction of the recess  22 , which is located near the proximal end of the firing pin  20  and the safety catch  13  which is located at the proximal end of the safety catch arm  16 . The proximal section of the first longitudinal bore  34  has a larger diameter than the distal section of the bore or receiving hole  34 . When the firing pin  20  is in the rest position, the rear or proximal end of the firing pin  20  protrudes from the proximal end of the second longitudinal receiving bore  35  and extends into the travel path of the hammer  32 . Further, when the firing pin  20  is in the rest position, the tip, or front, of the firing pin  20  is spaced so that it does not protrude from the bolt face  33 . 
     When the hammer  32  makes contact with the rear  23  of the firing pin  20 , the firing pin  20  moves forward against the force of the firing pin spring  21  until the firing pin  20  is protruding far enough to ignite the primer of a loaded cartridge (not shown) as seen in  FIG. 4 . In this illustrated example, the firing pin  20 , is of the “floating” variety in that, as a result of the hammer  32  striking the proximal end of the firing pin  20 , kinetic energy is transferred from the hammer  32  to the firing pin  20 , which imparts this transferred energy to the primer of the loaded cartridge. 
     As illustrated in  FIG. 1 , a guide groove  15  is milled into the side of the bolt carrier  30 . The guide groove  15  is a narrow opening which is milled from the outside surface of the bolt carrier into the hollow center of the bolt carrier group. The guide groove  15  has a section where the spring  11  is disposed at its distal end, and a bore  36  which transverses the guide groove  15  approximate its mid point for housing the roll pin  12  which secures the safety catch mechanism  10  in place. A coil type spring  11  is typically used to biases the safety catch arm  16  which is machined from steel. 
     The first longitudinal bore  34  is formed by the standard practices used to manufacture a bolt  31  for the M16 series of firearms. A round opening is present at both the proximal and distal ends of the first longitudinal bore  34  formed through the bolt  31 . 
     The second longitudinal receiving bore  35  extends from the distal end of the bolt carrier  30  to approximately its mid point. The bolt  31  operates, in general, substantially like a prior art bolt in a prior art bolt carrier. The distal end of the second longitudinal bore  35  is open to receive the bolt  31  and at the proximal end to receive the firing pin  20 . 
     The safety catch mechanism  10  has a portion, the safety catch  13 , which is machined on the proximal end and protrudes into the path of the firing pin  20 . The safety catch  13  has a caroming surface  14  machined onto its proximal end which increasingly extends into the travel path of the hammer  32 . The proximal end of the safety catch  13  is positioned just to the side and behind the proximal end of the firing pin  20 . 
     In the rest position illustrated in  FIG. 2 , safety catch  13  engages the recess  22  located at the proximal end of the firing pin  20 . The hammer  32  is in the cocked position. 
       FIG. 3  shows an example, of the herein described device, wherein the hammer  32  is released and moves forward and encounters and runs along the camming surface  14  of the safety catch mechanism  10 . When the hammer  32  encounters the camming surface  14 , it forces the safety catch  13  to the side against the spring  11  action on the rear part of the safety catch mechanism. As a result, the annular recess  22  and thus the firing pin  20  are released to move from the first position to the second position. The safety catch  13  then lies laterally against the hammer  32  and remains so positioned during the further movement of the hammer  32  so that the safety catch  13  remains situated in the release position. 
     The outer end of the annular recess  22  and the rear end of the safety catch  13  facing the firing pin  20  are each preferably provided with a chamfer. The chamfers on these surfaces are complementary. If the firing pin  20  is not moved back into its rest position after a shot is fired, the firing pin spring  21  forces the firing pin  20  and thereby the recess  22  back until the safety catch  13  engages the recess  22  surface. 
       FIG. 4  shows how after the hammer  32  strikes the proximal end of the firing pin  20 , the firing pin  20  moves forward since the safety catch  13  remains in its release position. When the firing pin  20  exits through the hole in the bolt face  33  it strikes the primer igniting the loaded cartridge (not shown). 
     During reloading, the bolt  31  pushes a new cartridge from the magazine (not shown) forward, into the chamber of the barrel (not shown) until the bolt  31  seats against the proximal end of the chamber (not shown). As the bolt  31  contacts the barrel chamber it rotates within the bolt carrier  30 . During this rotation of the bolt  31  the firing pin spring  21  is further compressed between the rear of the bolt  31  and the flange present along the distil end of the recess  22  located on the firing pin  20 . This increase of tension applies additional force to the firing pin  20  thereby moving it into its rest position. 
     From the foregoing, persons of ordinary skill in the art will appreciate that the disclosed firing pin safety device for auto-loading firearms is advantageous with respect to other prior art firing pin safety devices in that, for example, it may be adapted, with minor modifications, to the existing bolt carrier group used by the M16 family of firearms. Further it has very few moving parts allowing for higher operational reliability. The herein disclosed device is readily implemented into the M16 family of firearms. In particular, the disclosed device achieves these objectives by implementing a safety element including a safety catch mechanism  10 , spring  11  and roll pin  12  which is placed onto the existing bolt carrier design and interacts with the prior art firing pin. 
     In principle, it is possible to produce a safety catch mechanism by machining the parts from unhardened steel billet, and to heat treat it to the desired hardness. Other technologies such as metal injection molding may be used to reduce the cost associated with machining the parts from billet. The spring may be produced from any heat resistant steel that is capable of repeatedly bearing a load. A roll pin of hardened steel may be purchased from any number of suppliers. 
     During assembly, a spring  11  is placed within a void located at the distal end of the guide groove  15 . The safety catch mechanism  10  is placed in the groove  15  and depressed within. After the bore  36  for the roll pin  12  lines up with the void (not shown) in the safety catch mechanism  10 , located proximately in its center, the roll pin  12  is driven into place. This orientation has the proximal end, where the safety catch  13  is located, protruding into the hollow within the bolt carrier  30 . The guide groove  15  which houses the safety catch mechanism  10  supports the majority of its length to thereby prevent deflection during normal operation and to ensure reliable positioning of the safety catch  13  on the firing pin  20  recess  22 . The remaining assembly necessary is identical to that which is required in the prior art. 
     Conclusion, Ramifications, and Scope 
     Accordingly the reader will see that I have provided a firing pin safety device for auto-loading firearms which offers several advantages over the prior art. There herein, disclosed device prevents the unintentional discharge of a firearm which is the result of a “floating” firing pin. The herein described device will eliminate contact between the firing pin and the primer of a loaded cartridge which the firing pin is in contact with the safety catch mechanism. My device is designed to interact with the M16 family of weapons and the herein disclosures offers a means by which it may be incorporated, nevertheless this is not intended to limit the scope of this invention, rather, merely describe the preferred embodiment of the herein disclosed design. 
     While my above drawings and description contain much specificity, these should not be construed as limitations on the scope of the invention, but rather as an exemplification of one preferred embodiment thereof. 
     Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.