Abstract:
A stand-off breaching device, for breaching a target, that includes a nose at a front end which is a rounded cone-shape and configured to cause the stand-off breaching device to rebound from a target after the nose impacts the target, and a body connected to the nose and extending to a back end of the stand-off breaching device. The body includes a main explosive fill that is detonated and explodes to provide an explosive breaching force, and a delay detonator that detonates the main explosive fill and that is triggered when the nose impacts a target. The delay-detonator is configured to delay detonation of the main explosive fill until the stand-off breaching device has rebounded to a determined stand-off distance chosen to cause effective breaching of the target. The nose, body, and their components are fabricated from material that will be substantially consumed by the explosion, minimizing any fragments.

Description:
TECHNICAL FIELD 
     The technical field is explosive devices for breaching doors, and more particularly stand-off breaching devices that may be thrown or shot from a launcher. 
     BACKGROUND 
     Currently, dismounted troops have the capability to effectively breach medium weight steel doors using rifle-launched stand-off breaching devices such as the SIMON device and a similar U.S. Army derivative the GREM. Attempts are currently underway to develop a similar stand-off breaching capability which may be fired from a 40 mm grenade launcher. The 40 mm grenade is known as the Hell Hound. Both of these platforms have their advantages and disadvantages. 
     The SIMON is effective, but is not a compact device.
         Weight: 680 g (including stand-off rod)   Length:   Stand-off rod: 400 mm   Overall: 765 mm (30 inches)   Warhead diameter: 100 mm   Explosive fill:
           Standard SIMON: 150 g (PBXN-109)   SIMON 120: 120 g (PBXN-109)   
           Range: 15-30 meters
 
One of the most significant disadvantages of the SIMON device, and a significant cause of its lack of compactness, is its stand-off rod. The stand-off rod causes the SIMON device to be at least a certain distance from a door when its explosive detonates.
       

     The 40 mm grenade (Hell Hound) is compact, but its effectiveness is limited by its maximum payload and by the fact that it explodes on impact. A typical Hell Hound grenade has the following characteristics:
         Weight: 225 grams   Length: 110 mm (4.3 inches)   Explosive fill: 88 grams (A5)   Range: 400 m
 
Hell Hound grenades appear to be limited to a maximum explosive fill of less than 90 gram. Furthermore, as noted, the Hell Hound detonates on impact and does not rebound from the target, thereby preventing it from achieving an optimal stand-off distance.
       

     What is needed is a stand-off breaching device that combines the breaching effectiveness of the SIMON device and GREM with the compactness of the Hell Hound. To be effective, such a stand-off breaching device should produce minimal fragmentation and minimal blast hazards for the operator. 
     SUMMARY 
     Embodiments described herein have numerous advantages, including overcoming the defects of the prior art described above. These advantages may be achieved by a stand-off breaching device for breaching a target, such as a door. The stand-off breaching device includes a nose at a front end of the stand-off breaching device that is a rounded cone shape, the nose configured to cause the stand-off breaching device to rebound from a target after the nose impacts the target, and a body connected to the nose and extending to a back-end of the stand-off breaching device. The body includes a main explosive fill, in which the main explosive fill is detonated and explodes to provide an explosive breaching force, and a delay detonator that initiates the main explosive fill and that is triggered when the nose impacts a target. The delay detonator is configured to delay the detonation of the main explosive fill until the stand-off breaching device has rebounded to a determined stand-off distance chosen to cause effective breaching of the target. The nose and body, and components of each, are fabricated from material that will be substantially consumed by the explosion of the main explosive fill, minimizing any resultant fragments. 
     These advantages may also be achieved by a stand-off breaching device for breaching a target, the stand-off breaching device including means for activating means for delayed detonating of the stand-off breaching device, in which said activating means activates said delayed detonating means and causes the stand-off breaching device to rebound from the target upon impact with a target, a main explosive fill, in which the main explosive fill, when detonated, explodes and provides a explosive load on a target, and said delay detonating means, connected to said activating means, in which said delay detonating means detonates the main explosive fill after a delay designed to allow the stand-off breaching device to rebound to a desired stand-off distance from a target. Said activating means and said delay detonating means are substantially consumed by the explosion of the main explosive fill, minimizing any resultant fragments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description may refer to the following drawings, wherein like numerals refer to like elements, and wherein: 
         FIGS. 1A to 1D  are diagrams illustrating perspective, side, cross-sectional and partially exploded views of an embodiment of a stand-off breaching device. 
         FIG. 2  is a diagram illustrating a cross-sectional view of a body of an embodiment of a stand-off breaching device. 
         FIGS. 3A to 3D  are diagrams illustrating a perspective front, perspective rear, side and exploded views of a nose of an embodiment of a stand-off breaching device. 
         FIGS. 4A and 4B  are diagrams illustrating a safety pin extension of an embodiment of a stand-off breaching device. 
         FIG. 5  is a diagram illustrating a cross-sectional view of a nose bumper of an embodiment of a stand-off breaching device. 
         FIGS. 6A and 6B  are diagrams illustrating a cross-sectional view and rear perspective view of a firing pin retainer of an embodiment of a stand-off breaching device. 
         FIG. 7  is a diagram illustrating a cross-sectional view of a firing pin of an embodiment of a stand-off breaching device. 
         FIG. 8  a diagram illustrating a cross-sectional view of a safety pin retainer of an embodiment of a stand-off breaching device. 
         FIGS. 9A and 9B  are diagrams illustrating a cross-sectional view and a perspective view of a safety pin of an embodiment of a stand-off breaching device. 
         FIGS. 10A and 10B  are diagrams illustrating a front view and a perspective view of a safety disk of an embodiment of a stand-off breaching device. 
         FIGS. 11A to 11C  are diagrams illustrating an embodiment of a stand-off breaching device with fins. 
     
    
    
     DETAILED DESCRIPTION 
     Described herein are embodiments of a stand-off door breaching device and method. In an embodiment, the stand-off breaching device is a stand-off breaching grenade (“SOBG”) that may be accurately hand-thrown or launched by a grenade or similar launcher. Embodiments are designed with a delay detonator that is triggered by impact of the stand-off breaching device with a target (e.g., a door to be breached). The stand-off breaching device is also designed to rebound away from the target after impacting the target. In such embodiments, upon impact with the target, the delay detonator is initiated, the stand-off breaching device rebounds away from the target and, after a delay, the stand-off breaching device detonates. Embodiments are designed, and the delay detonator set, so that the stand-off breaching device detonates at some predetermined stand-off distance from the target. The delay-time of the delay detonator, and the speed with which the stand-off breaching device rebounds away from the door, determines the stand-off distance at which the stand-off breaching device detonates. Embodiments are also designed so that substantially all of the stand-off breaching device is consumed by the explosion, minimizing fragmentation and blast hazards. 
     The embodiments described herein, and indeed most door-breaching explosive devices, are found to most effectively breach a door when the device explodes at a “stand-off” distance away from the door. The desired stand-off distance is the distance at which the explosive loading on the door (the pressure on the door caused by the explosion) is sufficient to force open/breach the door. If the explosion occurs to close to the door, the explosive loading will tend to simply punch a hole in through the door rather than opening the door. If the explosion occurs to far from the door, the explosive loading will not be sufficient to open the door. The embodiments described here are designed to rebound to the effective, desired stand-off distance and explode, explosively loading the door with sufficient force to force the door open. The detonation delay for such embodiments may range from 75 to 100 ms. The stand-off distance for such embodiments may range from 8-14 inches. 
     The embodiments described herein are also designed to provide the effectiveness of the SIMON and GREM devices with the compactness of the 40 mm Hell Hound. Consequently, embodiments may have a similar amount of explosive fill as the SIMON 120 or even the standard SIMON. The amount of explosive fill used in embodiments of the stand-off breaching device may vary, as discussed in detail below, depending on the intended applications and effectiveness needed. For example, the explosive fill needed for breaching heavy-weight steel doors will necessarily be greater than that needed to breach medium-weight steel doors. 
     As noted above, embodiments are designed to be accurately and effectively hand-thrown. Such embodiments may have an effective range similar to that of the SIMON and GREM devices. However, the lack of a stand-off rod (which makes the device heavier and less compact and) and the more aerodynamic design of embodiments described here suggests that embodiments of the stand-off breaching device will have a greater effective thrown range than the SIMON and GREM devices. Embodiments of the stand-off breaching device may also be designed to be launched from a grenade launcher or similar device; such embodiments would likely have a similar effectiveness to the Hell Hound grenade. 
     With reference now to  FIGS. 1A-1D , shown are different views of an embodiment of the stand-off breaching device  100 . The stand-off breaching device shown is a stand-off breaching grenade (SOBG).  FIG. 1A  illustrates a perspective side view of SOBG  100 . As seen in  FIG. 1A , SOBG  100  looks like a standard ballistic shell. The side view shown in  FIG. 1B , however, illustrates some clear differences between a standard shell and SOBG  100 . For example, SOBG  100  includes a nose  102  and a body  104  with a gap between nose  102  and body  104 . This gap, as shown and discussed in detail below, enables nose  102  to compress into body  104  upon impact with target, thereby triggering delay detonator. 
     With reference to  FIG. 1C , shown is a cross-sectional view of SOBG  100 . Nose  102  and body  104  are shown in more detail. In cross-sectional view shown, embodiment nose  102  includes nose bumper  106 , safety pin extension  108 , safety pin retainer  110 , safety pin  112 , compression spring  114 , ball bearings  116 , and firing pin assembly  118 . Bumper  106  may be made from material, such as rubber, that will have some give and cause SOBG  100  to bounce away from target after impact of SOBG  100  with target. For example, bumper  106  may be made from vulcanized nitrile rubber or similar material. Upon impact with target, bumper  106  compresses and then rebounds to its original shape, exerting force against target and SOBG  100 , causing SOBG  100  to rebound or bounce away from target. Impact with target also causes nose  102  to be forced into body  104 , arming SOBG  100  and initiating delay detonator. 
     Safety pin  112  prevents SOBG  100  from being accidentally armed and detonator triggered prior to throwing of SOBG  100  against target. Safety pin retainer  110  holds safety pin  112  inside safety pin extension  108  which connects safety pin  112  with bumper  106 . Together with safety pin extension  108 , safety pin  112  and safety pin retainer  110  form a safety pin assembly. Compression spring  114  connects safety pin  112  to firing pin assembly  118  and keeps safety pin  112  separated from firing pin assembly  118  and, therefore, keeps firing pin assembly  118  from triggering delay detonator, during normal handling of SOBG  100 . Only when nose  102  impacts a target with sufficient force to move safety pin  112  with sufficient force to overcome inertia of compression spring  114  will compression spring  114  be compressed sufficiently to allow ball bearings  116  to disengage from housing  122  through the outside diameter contour of safety pin  112 . With the ball bearings  116  disengaged from housing  122 , the firing pin assembly  118  will be forced further into the body  104 , impact the primer  126 , and initiate the explosive train. Firing pin assembly  118  may include tip  120  (in affect, the firing pin) or other extension that impacts with primer to trigger detonation (see below). 
     It is noted that nose  102  may have different components than those shown and that the components shown may be shaped or configured differently. Such different components should cooperate and function in a manner consistent with the operation described above so that SOBG  100  does not detonate during routine handling, when thrown or shot at target, triggers delay detonator and bounces off of target upon impact with target, and detonates at ideal stand-off distance sufficient to force open target. 
     With continuing reference to  FIG. 1C , in cross-sectional view shown, embodiment of body  104  includes housing  122 , firing pin retainer  124 , primer  126 , delay detonator delay element  128 , delay detonator output/primary charge  130 , main explosive fill  134 , and back cap  136 . Housing  122  contains explosive fill  134  and the other components of body  104 . Firing pin retainer  124  retains firing pin assembly  118  inside body  104  of SOBG  100 . Primer or percussion cap  126  ignites delay detonator delay element  128 . Primer  126  is a low-energy, high-sensitivity explosive triggered by impact of tip  120  of firing pin assembly  118 . For example, primer may be a commercial, off-the-shelf (“COTS”) primer such as a Remington™209 Premier™ STS™ Primer, or a specifically designed primer. 
     In an embodiment, delay element  128  is a pyrotechnic delay element that burns. Time that delay element  128  takes to burn provides delay and is configured to delay sufficiently for SOBG  100  to rebound to ideal stand-off distance after impacting with target. Delay element  128 , after burning, ignites delay detonator output/primary charge  130 . Delay detonator comprises delay element  128  and primary charge  130 . Primary charge  130  detonates explosive fill  134  (secondary charge or explosive). Explosive fill  134  then detonates, with explosive shockwave of explosive fill  134  traveling back towards nose  102  of SOBG  100  (and, therefore, towards target). Explosive fill  134  may be a COTS explosive or a specifically designed explosive. In embodiments, explosive is a safety-certified explosive such as PBXN-109. Back cap  136  seals back end of body  104 . Back cap  136  shown is configured as flat circular disks that extend through entire circumference of interior (hollow space) of housing  122 , although different shapes may be used. 
     To summarize the delay detonation chain, upon impact of the SOBG  100  with the target, nose  102  pushes firing pin  118  into percussion primer  126 . Primer  126  sets off the delay element  128  in the time delay detonator, which burns and then sets off primary charge  130  of delay detonator. Primary chare  130  of delay detonator sets off booster  132 , which in turn sets off main explosive fill  134 . The time taken by the above-described detonation process provides the delayed detonation describe above. Accordingly, this process is configured by design and set-up to provide sufficient delay for an explosion of SOBG  100  at ideal stand-off distance from target. This configuration, therefore, takes into account amount of ‘bounce’ achieved by impact of nose bumper  106  on target under ordinary use (i.e., how far SOBG  10  will rebound from target in given amount of time—the rate, allowing for variations in speed of impact (e.g., as thrown by different persons at different speeds or launched by launchers), and ideal stand-off distance for given target type. In an embodiment the detonation delay may range from 75 to 100 ms, while the desired stand-off distance ranges from 8-14 inches. Accordingly, in such an embodiment, SOBG  100  may rebound from the target at about 0.08 to 0.19 inches per ms after impacting the target. 
     This rate of rebound and, therefore, the detonation delay, will vary depending on numerous factors including whether SOBG  10  is thrown or launched, how hard it is thrown, the weight of SOBG  10 , aerodynamic variations, etc. Likewise, the desired stand-off distance may differ based on the target, the explosive used and other factors. Ideally, these factors are all taken into account when designing and calibrating an implementation of SOBG  10  or other stand-off breaching device according to the present invention. 
     It is noted that the amount of main explosive fill  134  and the location of back cap  136  are not limited to what is shown in the accompanying drawings. More or less main explosive fill  134 , for example, may be provided depending upon the intended target and use of SOBG  100 . If greater explosive loading is needed, more explosive fill  134  may be used, and vice-versa. Furthermore, the affect of the amount and weight of main explosive fill  134  on the throwing balance of SOBG  100  may dictate that less or lighter main explosive fill  134  be used. For example, explosive fill  134  that extends to back cap  136  may cause the center of gravity of SOBG  100  to be to far to the back of SOBG  100 , causing SOBG  100  to tumble in flight. In such circumstances, the amount of main explosive fill  134  may need to be reduced, lighter explosive fill may need to be used or counter-balances (e.g., heavier materials used or additional counter-balancing components added) included in the front of SOBG  100 . 
     Accordingly, in an embodiment, main explosive fill  134  does not extend all the way to back cap  136 . Such an embodiment may include an interior back cap that encloses main explosive fill  134  and creates an empty space between end of main explosive fill  134  and back cap  136 . In such an embodiment, delay detonator may be shorter so that it does not extend beyond interior back cap and end of main explosive fill  134 . Alternatively, if delay detonator extends to back cap  136  as shown, a booster that surrounds primary charge  130  of delay detonator may be provided. In such an embodiment, explosive booster acts as a bridge between delay detonator and explosive fill  134 . Booster may wrap around primary charge  130  of delay detonator. Booster may be a COTS booster or specifically designed booster. In embodiments, the booster material is a safety-certified booster material. Booster is ignited by detonation of delay detonator primary charge  130 , increasing explosive shockwave to degree sufficient to detonate main explosive fill  134 . 
     Likewise, as noted, SOBG  100  may be designed to be hand-thrown or fired from a launcher. Accordingly, SOBG  100  be made built to a size comfortable for an average soldier to throw. The length, width and weight of such an embodiment of SOBG  100  should probably be on the same scale as an ordinary grenade, although perhaps a bit larger in all aspects since a SOBG  100  usually does not need to be thrown as far. In an embodiment, SOBG  100  is of a size and shape that is compact, so that it may be easily carried, and can be easily thrown by hand from a distance ranging from 5 to 10 meters. For such an embodiment, the expected safe usage distance of the SOBG  100  will be 5 to 10 meters. If designed to be fired, SOBG  100  may be larger in at least weight, although it will be restricted by launch capabilities of launcher. SOBG  100  may, therefore, be designed to fit within a launcher. Alternatively, an extension may be fitted to back-end of body  106  to fit inside launcher. In this manner, extension may extend out of back-end of body  106  into launcher when SOBG  100  is prepared for use. Back cap  136  may be configured to accept extension. As SOBG  100  may have its own launch tube attachment or system, SOBG  100  is not restricted to the 40 mm diameter or maximum length of the 40 mm grenade. Further, SOBG  100  weight may be increased because SOBG  100  will be launched at a much lower velocity than a standard 40 mm grenade because SOBG  100  needs to impact at a relatively low velocity to rebound (too fast a velocity and SOBG  100  will simply pass through some light-weight doors). 
     With continuing reference to  FIG. 1C , components of SOBG  100  are designed to be substantially consumed by explosion, thereby reducing or eliminating fragmentation effects. Consequently, material used to make components of nose  102  and body  104  described herein may be a plastic or other consumable material. For example, components may be made from polyoxymethylene (“POM”), an engineering thermoplastic. POM, also known as acetal, polyacetal, and polyformaldehyde, is known for is high-strength, hardness and rigidity and is readily used to manufacture precision parts. POM parts have been shown to be generally completely consumed by explosion of explosive fill  134 . A number of commercial suppliers of POM exist, including DuPont (Delrin™), Ticona (Hostaform™), Polyplastic (Duracon™), Korea Engineering Plastics (Kepital™), Mitsubishi (Lupital™) and BASF (Ultraform™). Other plastics or materials that may be used to fabricate precision parts such as components described above, that will be readily consumed by explosion of explosive fill  134 , and that do not otherwise produce hazardous effects, may be used. 
     With reference now to  FIG. 1D , shown is a perspective side view of embodiment of SOBG  100  with nose  102  removed from body  104 . Bumper  106 , safety pin extension  108 , ball bearings  116 , firing pin assembly  118  and tip  120  of nose  102  may be seen. Housing  122  and back cap  136  of body  104  may be seen 
     With reference now to  FIG. 2 , shown is a cross-sectional view of an embodiment of housing  122 . Housing  122  shown does not include firing pin retainer, primer, booster, main explosive fill, first back cap or second back cap. In an embodiment, these components are fabricated/manufactured separately from housing  122 . After fabrication, the components may be assembled with and installed in housing  122  to form body  104 . As shown, housing  122  defines a main cavity  202 , a firing pin cavity  204  and a primer cavity  206 . Main cavity  202  is hollow space, surrounded on all but open bottom or back of housing  122  by walls of housing  122 , in which main explosive fill, delay detonator, booster, and back cap are placed. Firing pin cavity  204  is hollow space, surrounded by walls of housing  122  except at open top or front of housing  122  and at primer cavity  206  location, where firing pin retainer  124  and firing pin assembly  118  of nose  102  are placed. Primer cavity  206  is hollow space, connecting main cavity  202  and firing pin cavity  204 , in which primer  126  is placed. Primer cavity  206  may be designed to securely hold primer  126  in place. 
     With reference now to  FIGS. 3A-3D , shown are various views of an embodiment of nose  102 . With reference to  FIG. 3A  and  FIG. 3B , shown are front and rear perspective side views of a fully assembled nose  102 . Shown are nose bumper  106 , safety pin extension  108 , firing pin assembly  118 , ball bearings  116  and tip  120 . Also shown is a notch (not labeled) in firing pin assembly  118 ; notch enables firing pin assembly  118  to be held by wrench during assembly. With reference to  FIG. 3C , shown is a side view of nose  102 , which illustrates the same components. 
     With reference now to  FIG. 3D , shown is an exploded view of an embodiment of nose  102  in which components of nose  102  may be seen more clearly. As discussed above, nose  102  may include nose bumper  106  (which provides ‘rebound’ of SOBG  100  from target), safety pin extension  108  (which connects safety pin  112  to nose bumper  106 ), safety pin retainer  110  (which retains position of safety pin  112  in safety pin extension  108 ), safety pin  112  (which must be forcefully depressed with sufficient force to overcome inertia of compression spring  114  in order to activate firing pin  118 ), ball bearings  116  (which enable nose  102  to “snap” into body  104  and enable firing pin assembly  118  to move smoothly inside housing  122 ), firing pin assembly  118  (in which safety pin  112  rests prior to activation) and tip  120  which impacts primer/detonation cap  126 , triggering delayed detonation of embodiment of SOBG  100 . 
     With reference now to  FIGS. 4A-4B , shown are a cross-sectional side view and a side view of an embodiment of safety pin extension  108 . As discussed above, safety pin extension  108  connects safety pin  112  to nose bumper  106 . As seen in  FIG. 4A , safety pin extension  108  includes a front portion  402  which may be used to secure safety pin extension  108  to nose bumper  106 , a flange portion  404  that extends outwards and is designed to provide a continuous, aerodynamic surface between nose bumper  106  and body  104 , and a safety pin sleeve  406 , through which safety pin  112  extends. Safety pin sleeve  406  defines a safety pin cavity  408  into which safety pin  112  is inserted. As shown, safety pin cavity  408  extends through safety pin extension  108 . This enables nose bumper  106  to come into contact with safety pin  112  when nose  102  impacts a target. In this manner, nose bumper  106  transfers sufficient force to safety pin  112  (i.e., force of impact) to depress safety pin  112  and overcome inertia of compression spring  114 , thereby activating firing pin  118 . 
     With reference now to  FIG. 5 , shown is cross-sectional side view of an embodiment of nose bumper  106 . Nose bumper  106  includes bumper portions  502  surrounding and defining a safety pin extension cavity  504  and a nose cavity  506 . Safety pin extension cavity  504  is location in which front portion  402  of safety pin extension  108  is inserted to secure safety pin extension  108  to nose bumper  106 . Safety pin  112  extends through safety pin extension  108  into safety pin extension cavity  504 . A flat portion at top of safety pin extension cavity  504  (against which top of safety pin  112  rests) may be defined as shown. Nose cavity  506  is hollow portion of nose bumper  106  defined by bumper portions  502  at center of nose bumper  106 , extending from tip of nose bumper  106  to safety pin extension cavity  504 . Safety pin  112  rests against underside of nose bumper  106  at bottom of the nose cavity  506 . In this configuration, impact force of nose  102  hitting target is more directly transferred to safety pin  112 . 
     With reference now to  FIGS. 6A and 6B , shown is a cross-sectional side view and a perspective rear-view of an embodiment of firing pin retainer  124 . Firing pin retainer  124  is placed in firing pin cavity  204  of housing  122  and retains firing pin assembly  118  in place in housing  122 . As shown, firing pin retainer  124  includes ring-shaped outer portion  602  and interior lip portion  604 . Outer portion  602  rests in firing pin cavity  204 . Interior lip portion  604  holds firing pin assembly  118  in place. Together, portion  602  and portion  604  define hollow area in which firing pin assembly  118  sits. 
     With reference now to  FIG. 7 , shown is a cross-sectional side view of an embodiment of firing pin assembly  118 . Firing pin assembly  118  may be configured as a hollow cylinder-shape housing containing safety pin  112  and compression spring  114 . Firing pin assembly  118  includes tip  120 , as discussed above, housing walls  702  defining safety pin/spring cavity  704  and spring lodgment  706  and ball-bearing cavities  708 . Compression spring  114  bottom end rests in spring lodgment  706  and extends upward into safety pin/spring cavity  704 . Safety pin  112  rests against compression spring  114  in safety pin/spring cavity  704 . Ball bearings  116  are situated in ball-bearing cavities  708 . 
     With reference now to  FIG. 8 , shown is a cross-sectional side view of an embodiment of safety pin retainer  110 . Safety pin retainer  110  may be configured as a hollow cylinder-shape containing safety pin  112 . Safety pin retainer  110  may include walls  802  that define retainer cavity  804  and retainer lip  806 . Safety pin  112  extends through cavity  804 , with wider portion of safety pin  112  resting against retainer lip  806 . 
     With reference now to  FIGS. 9A-9B , shown are a cross-sectional side view and a perspective side view of an embodiment of safety pin  112 . Safety pin  112  includes threaded portion  902  and gradually widening body portion  904 . Threaded portion  902  extends through safety pin retainer  110 , threads into safety pin extension  108  and into nose bumper  106 , as described herein. Gradually widening body portion  904  rests against retainer lip  806  of safety pin retainer  110  and extends into safety pin/spring cavity  704  of firing pin assembly  118 . Neck portion  902  defines neck cavity  904  which allows smooth transition for movement of ball bearings  116  during impact. Gradually widening body portion  904  defines spring cavity  908  in which compression spring  114  top end rests. 
     With reference now to  FIGS. 10A-10B , shown are front and perspective side views of an embodiment of a safety disk assembly  1000 . Safety disk assembly  1000  may be inserted into space between nose  102  and body  104  of an embodiment of SOBG  100 . As shown, safety disk assembly  1000 , or simply safety disk  1000 , may define open end  1002  that is slid over and around portion of safety pin extension  108  and safety pin retainer  110  that are exposed in space between nose  102  and body  104 . Placed in between nose  102  and body  104 , safety disk  1000  prevents safety pin  112  from being depressed into firing pin  118 . Safety disk  1000  also includes studs  1004  that enable safety disk  1000  to be pulled by hand. These studs  1004  may be omitted. 
     With reference now to  FIGS. 11A-11C , shown are various views of an embodiment of a SOBG  1100  with fins. With reference to  FIG. 11A , shown is a side view of an embodiment of SOBG  1100  with fins—fins not deployed. Embodiment of SOBG  1100  includes a nose  1102  and a body  1104 , which may have characteristics and features similar to nose  102  and body  104  described above. For example, nose  1102  may include a bumper and SOBG  1100  may include a gap between nose  1102  and body  1104 . This gap enables nose  1102  to compress into body  1104  upon impact with target, thereby triggering delay detonator. Body  1104  may be tapered at end opposite nose  1102 , as shown. SOBG  1100  further includes fins  1106  which may be unfolded or deployed prior to throwing (or during launching) of SOBG  1100 . Fins  1106  may provide more stable flight characteristics or impart other desired flight behavior(s) (e.g., such as spin) on SOBG  1100 . Fins  1106  may be attached to body  1104  via, e.g., hinges  1108 . SOBG  1100  may also include safety pin  1110  in gap between nose  1102  and body  1104 . Pin  1110  may prevent nose  1102  from being compressed into body  1104 , thereby preventing triggering of delay detonator, and is, therefore, removed before use of SOBG  1100 . 
     With reference to  FIG. 11B , shown is side view of an embodiment of SOBG  1100  with fins—fins deployed. As shown, embodiment of SOBG  1100  includes three fins  1106 . When deployed or unfolded, fins  1106  extend from back of body  1104  opposite nose  1102  end of SOBG  1100 . Other than fins  1106  and flight behavior(s) imparted by fins  1106 , SOBG  1100  may perform as other embodiments of SOBG described herein—impacting on target, bouncing off to desired stand-off distance, and detonating. 
     With reference now to  FIG. 11C , shown is a side, cross-sectional view of embodiment of SOBG  1100  with fins—fins deployed. As shown, body  1104  includes delay detonation mechanism  1116  and cavity  1114  that may contain main explosive fill. Also shown, nose  1102  includes extension that extends into body  1104  and triggers delay detonation mechanism  1116  upon impact with target. Delay detonation mechanism  1116  may be configured as described above or in a similar manner. Other delay detonation devices may be used. 
     As noted throughout, SOBG  100  shown and described herein is an embodiment. Many different variations on SOBG  100  are possible within the spirit of the invention. Variations based on payload, intended use (thrown or launched) or other conditions or factors may be taken into account when designing implementation of SOBG  100 . Stand-off breaching devices according to the invention combine the breaching effectiveness of the SIMON device and GREM with the compactness of the Hell Hound while producing minimal fragmentation and minimal blast hazards for the operator. Such stand-off breaching devices accomplish this by bouncing off of target and delay detonating upon reaching ideal stand-off distance range. Such stand-off breaching devices accomplish this by being throw by hand or launched. 
     A typical SOBG  100 , designed to be thrown, may weigh from 0.5 to 1.5 pounds and be approximately 2 to 6 inches in length and 1.5 to 3 inches in diameter. A typical SOBG  100 , designed to be launched from a launcher, may weigh from 0.5 to 1.5 pounds and be approximately 2 to 6 inches in length and 1.5 to 3 inches in diameter. Variations of these ranges are possible and expected based on different types of launchers, different throwing conditions, etc. 
     Likewise, although shown is two separate components, nose  102  and body  104  may be formed as one continuous component. Additional features, such as fins, rifling, tapering of body, or other physical variations may be provided to improve or change performance and/or flight characteristics. Similar variations to the embodiments described herein, and components thereof, are apparent to those of ordinary skill in the art and may be implemented. 
     The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention as defined in the following claims, and their equivalents, in which all terms are to be understood in their broadest possible sense unless otherwise indicated.