BULLET CONTAINMENT TRAP WITH A MODULAR BACKSTOP

Abstract

A bullet containment trap (1) with a modular backstop (7) is disclosed. The device (1) with the modular backstop (7) comprises of at least one open ended bullet receiving chamber (4), at least one electronic target assembly (not shown) configured to project at least one target placed at a rear end of the said open-ended bullet receiving chamber (4). The bullet fired compasses the said bullet receiving chamber (04) while in contact with boundary wall and enters a terminal part of said boundary wall over a throat (6) of a passageway and moves through said throat (6) to dissipate on hitting a modular backstop (7) of a deceleration chamber (5). The said modular backstop (7) with at least two impact zones are made by stacking multiple individual armored plates (12) vertically and/or horizontally in to a plurality of cassettes (11), wherein the said cassettes and/or the individual armored plates (12) within each of the said cassettes (11) are all replaceable for deformation.

Claims

1. A bullet containment trap device (1) with a modular backstop (7), wherein the device (1) comprises of: at least one electronic target assembly configured to project at least one target placed at a rear end of an open-ended bullet receiving chamber; the bullet receiving chamber (4) is supported by a plurality of supporting frames (2, 3); the said bullet receiving chamber (4) is backed with a bullet's deceleration chamber (5) in a horizontal axis and or in a vertical axis; the bullet fired compasses the bullet receiving chamber (1) while in contact with a plurality of boundary walls and enters a terminal part of said boundary wall over a throat (6) of a passageway and moves through said throat (6) to dissipate on hitting a modular backstop (7) of the said deceleration chamber (5); Characterized in that the said modular backstop (7) comprises a first impact zone (13) circumferentially oriented at a first angle from the horizontal zone of bullet travel and extends to at least one successive impact zone (14); the said modular backstop (7) with at least two impact zones are made by stacking multiple individual armored plates (12) vertically and/or horizontally in to a plurality of cassettes (11); the said cassettes (11) formed by stacking multiple individual armored plates (12) are held vertically and/or horizontally to form the said modular backstop (7), wherein the said cassettes (11) are joined with long bolts (8a) making the impinging loads of the bullet hitting the said backstop (7) distributed to multiple individual plates (12) of the said cassettes (11) closely stacked; and the said cassettes (11) and/or the individual armored plates (12) within each of the said cassettes (11) are all replaceable for deformation.

2. The device (1) as claimed in claim 1, wherein the said device (1) is used for de-energizing and collecting the bullet fired along a substantially horizontal path of flight.

3. The device (1) as claimed in claim 1, wherein the said bullet that enters the said deceleration chamber (5), even at a relatively low angle will move along the chamber without being shattered or damaging the walls or the modular backstop (7).

4. The device (1) as claimed in claim 1, wherein the spent bullet ultimately falls off the modular backstop (7), and are flushed into a passageway and then into a collecting vessel (10).

5. The device (1) as claimed in claim 1, wherein the modular backstop (7) comprises very high flexural bending strength compared to multilayered backstops.

6. The device (1) as claimed in claim 1, wherein the said cassettes (11) vertically held with support of long bolts (8) increases the compressive force making all the stacked plates behave like a single lumped block.

7. The device (1) as claimed in claim 1, wherein the deformation point is not constrained to single location on the modular backstop (7) of the device, but is distributed to locations which are at considerable distance.

8. The device (1) as claimed in claim 1, wherein the said cassettes (11) have configurable armored plates (12) and each plate has a configurable size.

9. The device (1) as claimed in claim 1, wherein the device (1) can also be rotated to be used in horizontal position by joining number of devices to form a larger device which can be used in both indoor and outdoor shooting ranges.

10. A method of replacing cassettes (11) and/or the individual armored plates (12) for deformation of the modular backstop (7) of the said bullet containment trap device (1), wherein the method comprises steps of: a. removing a plurality of long bolts (8) that locks a plurality of cassettes (11) formed of stacking multiple individual armored plates (12) vertically and/or horizontally (07); b. removing a back plate (18) and a plurality of side plates to get access to the said cassettes (11); c. identifying a damaged cassette (11) from the lumped block to repair and replace the damaged cassette (11) and/or the individual armored plates; d. removing a plurality of cassette locking bolts (8a) to remove damaged armored plates (12) of the said cassettes (11); and e. the modular backstop (07) of the said bullet containment trap device (1) allows cassettes (11) and/or the individual armored plates (12) within each of the said cassettes (11) to be easily replaced and/or repaired for deformation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The above and other objects, features and advantages of the invention will become apparent from a consideration of the following detailed description presented in connection with the accompanying drawings in which:

[0052] FIG. 1 illustrates a perspective of a bullet containment trap with a modular backstop, according to an exemplary embodiment of the present invention;

[0053] FIG. 2a illustrates a top sectional view of the deceleration chamber that comprises of the said modular backstop according to the exemplary embodiment of the present invention;

[0054] FIG. 2b illustrates a half sectional view of the deceleration chamber according to the exemplary embodiment of the present invention;

[0055] FIG. 2c illustrates a front view of a cassette, according to the exemplary embodiment of the present invention;

[0056] FIG. 3a illustrates a material characteristic of a bullet for steel core, according to the exemplary embodiment of the present invention;

[0057] FIG. 3b illustrates a material characteristic of the bullet for steel jacket, according to the exemplary embodiment of the present invention.

[0058] FIG. 3c illustrates a moderate strain rate compression test results for steel core and steel jacket, according to the exemplary embodiment of the present invention;

[0059] FIG. 3d illustrates a strain comparison for steel core and steel jacket, according to the exemplary embodiment of the present invention;

[0060] FIG. 4a-4b illustrates a velocity degradation of bullets, according to the exemplary embodiment of the present invention;

[0061] FIG. 5 illustrates a exploded side view of the said modular backstop according to the exemplary embodiment of the present invention;

[0062] It is appreciated that not all aspects and structures of the present invention are visible in a single drawing, and as such multiple views of the invention are presented so as to clearly show the structures of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0063] The present invention relates to a bullet containment trap for securing used bullets. Specifically, the invention relates to bullet containment traps, be used in conjunction with Containerized Tubular Shooting Range (CTSR) that is used for training purposes.

[0064] According to an exemplary embodiment of the present invention, a bullet containment trap with a modular backstop system for securing used bullets is disclosed. The said modular backstop system comprises of at least one electronic target assembly (not shown) configured to project at least one target placed at a rear end of an open-ended bullet receiving chamber. The said bullet receiving chamber is supported by a plurality of supporting frames. The said bullet receiving chamber is backed with a bullet's deceleration chamber in a horizontal axis wherein the bullet that is fired compasses the bullet receiving chamber while in contact with a plurality of boundary walls and enters a terminal part of said boundary wall over a throat of a passageway and moves through said throat to dissipate on hitting a modular backstop of the said deceleration chamber.

[0065] In accordance with the exemplary embodiment of the present invention, the said modular backstop with at least two impact zones is made by stacking multiple individual armored plates vertically and/or horizontally in to a plurality of cassettes.

[0066] In accordance with the exemplary embodiment of the present invention, the said modular backstop comprises a first impact zone circumferentially oriented at a first angle from the horizontal zone of bullet travel and extends to at least one successive impact zone.

[0067] In accordance with the exemplary embodiment of the present invention, the said cassettes formed by stacking multiple individual armored plates are held vertically and/or horizontally to form the said modular backstop, wherein the said cassettes are joined with long bolts making the impinging loads of the bullet hitting the said backstop distributed to multiple individual plates of the said cassettes closely stacked. The said cassettes and/or the individual armored plates within each of the said cassettes are all replaceable for deformation.

[0068] In accordance with the exemplary embodiment of the present invention, the said device is used for de-energizing and collecting the bullet fired along a substantially horizontal path of flight. The said bullet that enters the said deceleration chamber, even at a relatively low angle will move along the chamber without being shattered or damaging the walls or the modular backstop.

[0069] In accordance with the exemplary embodiment of the present invention, the device can also be rotated to be used in horizontal position by joining number of devices to form a larger device which can be used in both inside and outside ranges.

[0070] In accordance with the exemplary embodiment of the present invention, the spent bullet ultimately falls off the modular backstop, and are flushed into a passageway and then into a collecting vessel. the modular backstop comprises very high flexural bending strength compared to multilayered backstops.

[0071] In accordance with the exemplary embodiment of the present invention, the said cassettes vertically held with support of long bolts increases the compressive force making all the stacked plates behave like a single lumped block. The deformation point is not constrained to single location on the modular backstop of the device, but is distributed to locations which are at considerable distance. The said cassettes have configurable armored plates and each plate has a configurable size.

[0072] According to the exemplary embodiment of the present invention, a method of replacing cassettes and/or the individual armored plates for deformation of the modular backstop of the said bullet containment trap device is disclosed.

[0073] In accordance with the exemplary embodiment of the present invention, the method comprises a first step of removing a plurality of long bolts that locks a plurality of cassettes formed of stacking multiple individual armored plates vertically and/or horizontally. The said method comprises a second step of removing a back plate and a plurality of side plates to get access to the said cassettes. The said method comprises a third step of identifying a damaged cassette from the lumped block to repair and replace the damaged cassette and/or the individual armored plates.

[0074] In accordance with the exemplary embodiment of the present invention, the method comprises a fourth step of removing a plurality of cassette locking bolts to remove damaged armored plates of the said cassettes.

[0075] In accordance with the exemplary embodiment of the present invention, the modular backstop of the said bullet containment trap device (allows cassettes and/or the individual armored plates within each of the said cassettes to be easily replaced and/or repaired for deformation.

[0076] Reference will now be made to the drawings in which the various elements of the present invention will be given numeral designations and in which the invention will be discussed so as to enable one skilled in the art to make and use the invention. It is to be understood that the following description is only exemplary of the principles of the present invention, and should not be viewed as narrowing the pending claims. Additionally, it should be appreciated that the components of the individual embodiments discussed may be selectively combined in accordance with the teachings of the present disclosure. Furthermore, it should be appreciated that various embodiments will accomplish different objects of the invention, and that some embodiments falling within the scope of the invention may not accomplish all of the advantages or objects which other embodiments may achieve.

[0077] Referring to FIG. 1, the device (1) with a modular backstop (7) in accordance with an exemplary embodiment of the present invention is disclosed. The device (1) comprises of a bullet receiving chamber (4) for resisting penetration of bullet and to inhibit rebounding of bullet. The device (1) comprises of a top plate, bottom plate, and left and right plate placed in a rectangular shape to form an open-ended bullet receiving chamber (4), and a deceleration chamber (5), placed at a rear end of the open-ended bullet receiving chamber (4).

[0078] The said bullet receiving chamber (4) and deceleration chamber (5) is mounted in between supporting frames top (2) and bottom frame (3) with a wheel (4) and a collecting vessel (not shown) is placed below the deceleration chamber (5). The said bullet receiving chamber (4) means is backed with a bullet's deceleration chamber (5) in a horizontal axis.

[0079] Referring to FIG. 2a-2b the deceleration chamber (5) in accordance with the exemplary embodiment of the present invention is disclosed. The deceleration chamber (5) comprises of modular backstop (7), a plurality of cassettes (11) placed vertically and locked both sides with a nut (8) along with a back top fixing plate (9). A left and right impact plates are placed beside the modular backstop (7) to compass the bullet in its axis. Wherein the said back top fixing plate (10) also comprises of long vertical impact plates (15) are fixed at an angle in at least as great as the secondary angle which is placed on the top and bottom of the cassettes (11).

[0080] The bullet fired compasses the bullet receiving chamber (4) while in contact with boundary wall and enters a terminal part of said boundary wall over a throat (6) of a passageway and moves through said throat to dissipate on hitting a modular backstop (7) of the said deceleration chamber (5).

[0081] Referring to FIG. 2c the cassettes (11) in accordance with the exemplary embodiment of the present invention is disclosed. The cassette (11) comprises of individual armored plates (12) held vertically and/or horizontally to form the said modular backstop (7). Wherein, the said cassettes (11) are formed by stacking multiple individual armored plates (12) vertically and/or horizontally to form the said modular backstop (7). The said cassettes (11) are joined with long bolts (8) making the impinging loads of the bullet hitting the said backstop (7) distributed to multiple individual plates of the said cassettes (11) closely stacked.

[0082] Wherein the said cassette has configurable armored plates (12) and each plate has a configurable size, and is screwed with two bolts to engaged and remove cassette after damage. The said cassettes (11) and/or the individual armored plates (12) within each of the said cassettes (11) are all replaceable for deformation.

[0083] Referring to FIG. 3a, the material characteristics of bullet in accordance with the exemplary embodiment of the present invention is disclosed. The yield stress of the material is specified as a function of the equivalent plastic strain at different equivalent plastic strain rates. The material definition also includes failure models with progressive damage, which causes analysis software to remove elements from the mesh as they fail. Both the ductile and shear initiation criteria are used: the ductile criterion is specified in terms of the plastic strain at the onset of damage as a tabular function of the stress tri-axiality. The shear criterion is specified in terms of the plastic strain at the onset of damage as a tabular function of the shear stress ratio. The damage evolution energy is assumed to be 500 N/m. The armored plate of 10 mm thickness, a bullet of 33 mm in length and 7.82 mm diameter has an initial speed of 850 m/sec.

[0084] A 3D model of the device (1) is analyzed to understand the structural behavior for different bullet impacts in which 3 case studies were done. The armor plate and associated parts of device were assigned with AR500 material and bullet material properties were assigned with three core material like copper coated steel jacket, lead-antimony and steel.

[0085] A bullet fired from the center of the throat (Bulls Eye) in accordance with the exemplary embodiment of the present invention is shown. During the analysis elements from both bodies fail, which calls for the use of element-based surfaces that can adapt to the exposed surfaces of the current non-failed elements. The general contact algorithm supports element-based surfaces that evolve in this manner (whereas the contact pair algorithm does not). To model eroding contact, we must include in the contact domain all surface faces that may become exposed during the analysis, including faces that are originally in the interior of bodies. Only the interior faces that are expected to participate in contact are included in the contact domain in this analysis to minimize the memory use (including interior faces for all elements in the model would more than double the memory use).

[0086] By default, the general contact algorithm does not include nodal erosion, so contact nodes will still take part in the contact calculations even after all of the surrounding elements have failed. These nodes act as free-floating point masses that can experience contact with the active contact faces. The analysis is conducted including nodal erosion, which causes the nodes to be removed from the contact calculations once all surrounding elements have failed.

[0087] Material Characteristics of Bullet: a compression test of steel being used in accordance with the exemplary embodiment of the present invention is shown. Three different regimes of material's response to compression can be distinguished. After first, elastic response, with the modulus of elasticity of E1=31.72 GPa, and yield point of y=362 MPa, there are two strain hardening zones with stiffness of E2=1.24 GPa and E3=3.45 GPa, respectively, ending by load increase due to platen-to-platen compression.

[0088] Material Characteristics of Bullet: Referring FIG. 3b, compression test results of a copper plated steel jacket in accordance with the exemplary embodiment of the present invention is shown. Jacket showed to be stiffer, having Young's modulus of E=42.5 GPa as well as higher yield strength of y=603.3 MPa, then steel core. During compression, cylindrical test sample, after reaching the yield point, gets crushed including two buckling modes, indicated by two peaks on the graph.

[0089] Referring FIG. 3c to 3d, test results for stress and strain of a copper plated steel jacket and steel core, Compared, quasi-static and moderate strain rate compression results, for both bullet core and jacket (FIG. 3d-3e show initially stiffer response (marked on graphs) of both core and jacket at higher strain rate. However, it has to be noted that even moderate strain rate of 100 s.sup.1 is still much lower than strain rates that bullet materials experience during ballistic event, which are in order of 10,000 s.sup.1.

[0090] These above material characteristics were used for Bullet in our device simulation to know the strength of the armored plate. Material characteristics were evaluated by doing above physical tests with high strain rates in dynamic condition.

Bullet Material Properties

[0091]

TABLE-US-00001 Johnson - cook plasticity material model Bullet Component A [MPa] B[MPa] N M C 7.62*39 mm MSC - core 234.4 413.8 0.25 1.03 0.00333 7.62*39 mm MSC - jacket 448.2 303.4 0.15 1.03 0.00333 Lead filler 10.3 41.3 0.21 1.03 0.00333

TABLE-US-00002 Johnson - cook dynamic failure model Bullet Component D1 D2 D3 D4 D5 Steel core 5.625 0.3 7.2 0.0123 0 7.62*39 mm MSC - jacket 2.25 0.0005 3.6 0.0123 0 Lead filler 0.25 0 0 0 0 [0092] Damage Evolution type displacement=0.0001 [0093] Mie-gruneise equation of state (used on all the materials) [0094] c.sub.o=4.596E6 mm/s [0095] s=1.4 [0096] r.sub.o=1.93 [0097] Linear elastic shear modulus G=9.446E3 MPa

Armor Plate Material Properties

[0098] Density=7800 Kg/m.sup.3 [0099] Elastic Modulus=210 GPa [0100] Poisson's Ratio=0.28 [0101] Yield Strength=776 Mpa [0102] Ultimate Tensile Strength=1810 MPa

Assumptions for the Analysis:

[0103] AR-500 Material properties are assigned for DEVICE. [0104] Copper coated steel jacket and Lead-Antimony material properties were applied to the bullet. [0105] A non-linear dynamic analysis was performed to account for nonlinearity in the geometry and material. As it is a transient non-linear dynamic analysis inertial effects and whole kinetic energy of the bullet load will be applied and response will be calculated for every micro second. [0106] Steel coated copper jacket lead material are modeled in such a way that they have proper nodal connectivity between them. [0107] Bullet mass of 11.5 g and velocity of 850 m/s was considered [0108] Stresses are presented after removing spurious areas. [0109] Coefficient of friction was assumed as 0.2 between bullet and the device.

[0110] Analysis is performed by assuming an ideal condition in which no air gaps will be there and strength of the armor plate is analyzed for ideal conditions. But in field conditions there will be air traps or distorted crystal lattice structure at some locations of the components which will degrade the stiffness of the part causing fatigue failure while in operating conditions.

Mathematical Material Model

Material Constitutive Model

[0111] In general, the response of material under High-speed impact involves consideration of the effect of strain. Strain rate and temperature.

[0112] The Johnson-Cook material model with strain rate dependence was used in the simulation to define the inelastic behavior of die bullet materials.

[0113] The static yield stress .sup.0 is assumed to be of the form

.sup.0=[A+B(.sup.pl)n](1{circumflex over ()}.sup.m)

[0114] Where .sup.pl is the equivalent plastic strain and A, B, n and m are material parameters measured at or below the transition temperature .sub.transition {circumflex over ()} is the non-dimensional temperature defined as

[00001]$\hat{}=\left\{\begin{array}{c}0.fwdarw.<{}_{\mathrm{transition}}\\ \frac{\left(-{}_{\mathrm{transaction}}\right)}{\left({}_{\mathrm{melt}}-{}_{\mathrm{transition}}\right)}.fwdarw.{}_{\mathrm{transition}}{}_{\mathrm{melt}}\\ 1.fwdarw.>{}_{\mathrm{melt}}\end{array}\right\}$

[0115] Where is the current temperature, .sub.melt is the melt temperature and .sub.transition is the transition temperature defined as the one at or below which there is no temperature dependence on the expression of the yield stress.

[00002]$\stackrel{\_}{}={}^0\left({}^{\mathrm{pl}},\right)R\left({\stackrel{.}{}}^{-\mathrm{pl}}\right){\stackrel{.}{}}^{-\mathrm{pl}}={\stackrel{.}{}}_0\exp \left[\frac{1}{c}\left(R-1\right)\right]\mathrm{for}\stackrel{\_}{}{}^0$

[0116] The Johnson-Cook strain rate dependence assumes that [0117] Where, [0118] : yield stress at nonzero strain rate [0119] {dot over ()}.sup.pl: equivalent plastic strain rate [0120] {dot over ()}.sub.0: Reference strain rare [0121] C: Material parameters measured at or below the transition temperature [0122] .sup.0 (.sup.pl, ): is the static yield stress [0123] R({dot over ()}.sup.pl): is the ratio of the yield stress at nonzero strain rate 10 the static yield stress (so that R({dot over ()}.sub.0)=1.0)

[0124] The elastic behavior of the material was defined with a hydrodynamic material model, in which the pressure is defined as a function of the density and the internal energy.

Dynamic Failure Model for Lead Material

[0125] The Johnson-Cook dynamic failure model which is suitable for high-strain rate deformation of metals was used to define the lead failure in the high-speed ballistic impact simulation.

[0126] The model assumes that the equivalent plastic strain at the onset of damage. is a function of stress triaxiality and strain rate. The failure is assumed to occur when the damage parameter exceeds 1. The damage parameter w is defined as

[00003]$=.Math.\left(\frac{{}^{-\mathrm{pl}}}{{}_f^{-\mathrm{pl}}}\right)$

[0127] Where .sup.pl an increment of the equivalent plastic strain is, .sub.f.sup.pl is the strain at failure, and the summation is performed over all increments in the analysis. The strain at failure, .sub.f.sup.pl is assumed to be dependent on a non dimensional plastic strain rate,

[00004]$\frac{{\stackrel{.}{}}^{-\mathrm{pl}}}{{}_f^{-\mathrm{pl}}};$

a dimensionless pressure deviatoric stress ratio, p/q where p is the pressure and q is the mises stress; and the non dimensional temperature {circumflex over ()}. The dependencies are from

[00005]${}_f^{-\mathrm{pl}}=\left[D_1+D_2\exp \left[d_3\frac{p}{q}\right]\right]\left[1+d_4\ln \left[\frac{{\stackrel{.}{}}^{-\mathrm{pl}}}{{\stackrel{.}{}}_0}\right]\right]\left(1+d_5\hat{}\right)$

[0128] The stress on armored plate is illustrated, the results shows when a bullet gets fired from center of trough (6), the stress on armed plate is less than the stress on modular back stop, the said first impact zone (13) circumferentially oriented at a first angle from the horizontal zone has more stress and compared to one successive impact zone (14).

[0129] As the plates are stacked to form a rectangular block. This block will have very high flexural bending strength compared to old design causing negligible deflection. As the plates are stacked to form a rectangular block. This block will have very high flexural bending strength compared to old design causing negligible deflection. Irrespective of the bullet hitting direction the deformation point is not constrained to single location on the armor plate. It is distributed to two locations which are at considerable distance. Final Bullet impinging load will be distributed to minimum three to four plates.

[0130] If the plates wear further and make a cavity, the bullet goes inside the cavity and retards the speed of the bullet and stops. However, if cavity becomes big removing the distorted bullet can be done by removing the top plate.

[0131] The volume of the device has decreased nearly to th compared to the previous volume and the weight got decreased. Thickness of the armor plate can be increased to our convenience. As the plates are stacked, the self-weight of the plates and the long bolts which hold the plates in stacked manner will increase the compressive force making all the stacked plates behave like a single lumped block.

[0132] As the system is designed in modular cassettes, after the plates wear to considerable thickness, each module can be replaced with new cassette without disturbing the whole device.

[0133] All the possibilities of the bullet reverse travel were tested using dynamic analysis simulation and is observed that the bullet cannot travel in reverse direction after hitting the target. This system was tested with SLR bullet of weight 11.5 g with speed of 850 m/s. Kinetic Energy of the bullet is 4.15 kJ. When the bullet hits at bulls' eye (Case-1) the results show that the deflection on armor plate is 0.16 mm and could see elastic strains 0.00824 with stress of 633 MPa.

[0134] As the kinetic energy is 4154 J the total reaction force acting on the block is 415.4 kN which is equal to 42.34 tonnes acting for 0.0117 sec as a impulse shock. As the front nose cone of the SLR bullet is 0.5 mm thick with lead-antimony (Yield 15 MPa) content which is very soft in strength compared to steel (650 MPa) is smashed due to 0.5 mm thick copper coated steel jacket which causes the surface area of the bullet to increase causing the impact to spread to larger area of the plate.

[0135] Analysis results suggest that the device (01) with modular backstop (7) can withstand a greater number of bullet shots before its failure due to more thickness and high flexural bending strength. Its modular cassette (11) design will help us in replacing the distorted and deformed plates (12) easily.

[0136] Referring FIG. 4a-4b, Continuous firing of bullets within short time generates high temperatures and causes consequential material property changes of the back plates and leads to deformation in shape of the plates and finally allows penetration of bullets in to the back plates. Whereas in the present invention, the stacked armored plates each act as heat sink fin increases the surface area for heat dissipation.

[0137] As we know the thermal conductivity

[00006]$Q=\left(\frac{-\mathrm{KA}\left(T_2-T_1\right)}{L}\right);$

the thermal conductivity of the armored plates used in cassette type configuration will increase due to increase in surface area of the armored plates. The heat is dissipated due to conduction, and the modular backstop of the present invention will not deform due to heat accumulation as we see in the prior art bullet/projectile containment traps. Flexural bending strength of the modular backstop of the present invention is also managed due to high momentum of inertia in the bending direction.

[0138] Non linear impact dynamic analysis is performed to calculate velocity degradation of bullets being dissipated with respect to guide plates (6). Many iterations are been performed for smooth velocity degradation and accordingly a profile of the modular backstop is evaluated as shown in FIG. 4a-4b.

[0139] Referring to FIG. 5, a method of replacing cassettes (11) and/or the individual armored plates (12) for deformation of the modular backstop (7) of the said bullet containment trap device (1) is disclosed.

[0140] In accordance with the exemplary embodiment of the present invention, the method comprises a first step of removing a plurality of long bolts (8) that locks a plurality of cassettes (11) formed of stacking multiple individual armored plates (12) vertically and/or horizontally. The method comprises a second step of removing a back plate (18) and a plurality of side plates to get access to the said cassettes (11). The method comprises a third step of identifying a damaged cassette (11) from the lumped block to repair and replace the damaged cassette (11) and/or the individual armored plates.

[0141] In accordance with the exemplary embodiment of the present invention, the method comprises a fourth step of removing a plurality of cassette locking bolts (8a) to remove damaged armored plates (12) of the said cassettes (11).

[0142] In accordance with the exemplary embodiment of the present invention, the modular backstop (7) of the said bullet containment trap device (1) allows cassettes (11) and/or the individual armored plates (12) within each of the said cassettes (11) to be easily replaced and/or repaired for deformation.

[0143] Thus, there is disclosed an improved bullet containment trap with a modular backstop. Those skilled in the art will appreciate numerous modifications which can be made without departing from the scope and spirit of the present invention. The appended claims are intended to cover such modifications.