US3447806A

US3447806A - Bullet trapping assembly

Info

Publication number: US3447806A
Application number: US553744A
Authority: US
Inventors: Herbert Pfaff; Walter Lasseur; Friedhelm Hillebrand
Original assignee: Kloeckner Werke AG
Current assignee: Kloeckner Werke AG
Priority date: 1965-06-05
Filing date: 1966-05-31
Publication date: 1969-06-03
Anticipated expiration: 1986-06-03
Also published as: NL6607773A; GB1078590A; CH440041A; BE681425A; FR1450217A; DE1273374B

Description

sheet of 2 June 3, 1969 H, PFAFF ErAL BULLET TRAPPING ASSEMBLY Fild May 51, 1956 wma June 3, 1969 H, PFAFF ETAL 3,447,806

BULLET TRAPPING ASSEMBLY Filed May 3l, 1966 Sheet 'e of 2 United K Int. Cl. A63b 67/0, 69/00, 71/00 U.S. Cl. 273-102.4

7 Claims ABSTRACT F THE DISCLQSURE A bullet trapping assembly in which the bullets are deflected by a panel formed by compound casting steel plates on a downwardly inclined top wall of a chamber into a water basin formed by the chamber.

.The present invention relates to improvements in bullet trapping assemblies for use in shooting ranges. More particularly, the invention relates to improvements in bullet deecting and collecting components of bullet trapping assemblies.

It is an important object of the present invention to provide a relatively simple and inexpensive but exceptionally safe bullet trapping assembly which may be constructed in any desired size and which is useful in military as well as in civilian shooting ranges.

Another object of the invention is to provide a bullet trapping assembly which requires a minimum of maintenance and wherein, after having pierced or missed the target, each projectile is caused to ricochet in a predetermined direction without causing any damage to the structural components of the assembly and without rep resenting any danger to the persons using or operating the shooting range.

A further object of the invention is to provide a bullet trapping assembly which can be used practically all year round, which can accommodate a year's supply or more of spent projectiles, and wherein such spent projectiles may be collected and removed in a very simple and time saving manner.

An additional object ofthe invention is to provide a bullet trapping assembly wherein bullets reaching or entering the actual trap cannot produce dust clouds to obscure the vision of participants in target practice and wherein spent bullets can be caused to automatically accumulate in a predetermined area to facilitate their removal from the trap.

A concomitant object of the invention is to providev a novel casing for the trap of a bullet trapping assembly and to construct the casing in such a way that all of its zones are readily accessible and that its chamber may be evacuated, cleaned and refilled in a time saving operanon.

Briefly stated, one feature of our invention resides in the provision of a bullet trapping assembly for use in pistol ranges, rifle ranges and other types of shooting ranges. This assembly comprises a casing having a chamber containing a body of water or other suitable liquid filling the chamber to a level below the line of fire, a front opening provided in the chamber for entry of bullets, and a downwardly inclined top wall extending rearwardly of the front Y opening and making an acute angle with the line of lire so that a bullet penetrating through the front opening rebounds or richochets on the 4top wall and enters the body of liquid. In accordance with another feature of our invention, the top wall preferably comprises a panel or liner consisting at least in part of hard metallic material, preferably two or more layers of compound steel including a lowermost layer of relatively hard steel and a layer 3,447,806 Patented June 3 1969 adjacent to the lowermost layer and consisting of relatively soft steel. The transition between such layers is preferably gradual so that the hardness of the intermediate zone varies gradually between the higher and-the lower hardnesses. The bullets rebound at the underside 'of the lowermost layer and are caused to descend into the body of liquid to accumulate on the bottom wall of the casing.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved bullet trapping assembly itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be ybest understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. l is a horizontal section through a bullet trapping assembly which embodies our invention;

FIG. 2 is a vertical section as seen in the direction of arrows from the line II--II of FIG. 1;

FIG. 3 is an enlarged fragmentary vertical section through a bulletproof liner or panel which may be utilized in theassembly of FIGS. 1 and 2; and

FIG. 4 is a s imilar fragmentary section through a different liner- Referring to the drawings in detail, and first to FIGS. 1 and 2, there is shown a bullet trapping assembly comprising a firing tunnel l which may comprise side walls consisting of concrete or the like and extends above the ground level shown at G. The actual bullet trap of the assembly comprises a casing or housing 2 defining a chamber 2A whose front opening 2a is located in the line of lire, i.e., in registry with the rear end of the tunnel 1, and whose lower part is filled with a supply 3 of water or other suitable liquid extending to a level 3a which is located below the line of fire and below the level of the ground G. ln accordance with a very important feature of the present invention, the top wall of the casing 2 comprises a panel or liner 5 consisting of metallic material and having an exposed bottom surface which faces the body of liquid 3 and extends downwardly and rearwardly of the front opening 2a so that its rear end portion 5a terminates at or near to the liquid level 3a. As clearly shown in FIG. 2, the panel 5 extends across the entire line of fire but makes therewith a relatively small acute angle so that any bullet passing through the tunnel 1 and piercing a target (not shown) which is placed across the rear end portion of the tunnel will travel through the front opening 2a and will impinge against the panel 5 to rebound into the liquid 3. The preferred composition of the panel 5 will be described in connection with FIGS. 3 and 4;,it suffices to say here that this panel preferably consists of compound metal, most preferably compound steel, and that at least the material adjacent to the underside of the panel 5 consists of relatively hard metallic material which cannot be pierced or de formed by bullets, even by bullets fired from a high-` powered rieor an analogous weapon. The body of liquid 3 offers a considerable resistance to bullets l5 which rebound on the panel 5 so that such bullets rapidly lose speed and descend onto the downwardly and rearwardly inclined bottom wall 2b of the casing 2. The inclination of the bottom wall 2b may be such that at least some of the bullets l5 will tend to roll toward a depression or recess 2c provided in the rearmost and lowermost portion of the bottom wall. This depression 2c accommodates a steel tray, a steel basket or a like receptacle 7 which may be withdrawn from time to time by means of a crane or the like to evacuate the bullets. The receptacle 7 may be withdrawn through an opening (not shown) in the top wall of the casing 2, Any bullets which fail to enter-the lepression 2c may be swept or otherwise forcibly ad fanced into the receptacle 7 subsequent to evacuation of he liquid body 3. The

side walls

2d, 2e and the bottom vall 2b will preferably consist of concrete or other masony material. Also, the top wall lof the casing 2 preferably :omprises a roof layer 4 of concrete plates which serve 1s a means for supporting the panel 5. The rearmost (lowermost) portion of the roof layer 4 is horizontal or nearly horizontal. The rear end of the firing tunnel 1 is separated from the adjoining portions of the casing 2 by a series of elastic inserts or compensators 16 which can expand or contract to thus compensate for eventual dif- Eerences in expansion coefficients of materials of which the tunnel 1 and the adjoining portion of the casing 2 consist.

The bottom wall 2b of the casing 2 can be reached by personnel in charge through the front opening 2a and by using stairs 14 which lead from the ground level G to the upper part of the bottom wall.

In accordance with another feature of our invention, the casing 2 4may be made integral with a second casing 6 which defines a second chamber 6A located directly behind the chamber 2A. This casing 6 has a top wall provided vvith a port hole 11 and a bottom wall provided with a sump 9. An overow passage connects the chamber 2A, 6Ay at the liquid level 3a, and a second passage 8 connects these chambers at the bottom level of the casing 2.. An automatic pump 17 (indicated in FIG. 1 by broken lines) is installed in the chamber 6A to pump liquid through the lower passage 8 whereby the liquid overflows through the upper passage 10 and is recirculated as long as the pump 11 remains in operation. A nor-mally sealed outlet 12 allows for evacuation of liquid from the

chambers

2A and 6A. The outlet 12 may also serve as an inlet for admission of a fresh supply of liquid. A set of metallic stairs 13 is provided on a side wall of the casing 6 to facilitate access to the pump 11.

Referring now to FIG. 3, there is shown a portion of a plate which may be utilized to form the entire or a portion of the panel or liner 5 shown in FIG. 2. This plate comprises a relatively hard lower layer ai and a relatively soft lbut tough upper layer b. The plate of FIG. 3 is prefably formed by compound casting, for example, as disn closed in U.S. Patent N-o. 1,710,931 or in U.S. Patent No. 3,237,908 to Harnisch et al., the latter patent being assigned to the assignee of the present application. There is an intermediate zone (not shown) which is disposed between the layers a and b, and the hardness of such intermediate zone preferably varies gradually between the hardness of the relatively hard layer a and the hardness of the relatively soft layer b. The intermediate zone may be relatively thick.

The plate of FIG. 4 comprises a relatively soft median steel layer b which is sandwiched between two relatively hard outer steel layers a. Again, the plate of FIG., 4 preferably comprises two relatively thick intermediate zones each provided between the layer b and one of the outer layers a and each having ya gradually varying hardn ness. The lines separating the layers a `and b of FIG., 3 or the layer b from the outer layers a of FIG. 4 are assumed to extend midway through the aforementioned in1 termediate zones. The panel or liner 5 of FIG. 2 may be assembled -of two or more coplanar plates.

A very important advantage of the casing 2 whose lower part constitutes a water basin and of the inclined panel 5 is that each bullet which has penetrated through the front opening 2a of the chamber 2A- richochets or rebounds in a fully predictable way, namely, toward the liquid level 3a. In this fway, the rear wall, the bottom wall 2b and the

side walls

2d, 2e of the casing 2 are not damaged yat all and the rebounding bullets constitute no danger to persons at the shooting range where the assernfbly of our invention, is put to use., Also, spent bullets may be accumulated and removed in a very simple and time saving operation.

.A further very important advantage of the bullet trapping assembly shown in FIGS. 1 and 2 is that it may be erected and operated at a very low cost. Moreover, the length of intervals during which the assembly must be shut down for cleaning and removal of bullets is reduced beyond any expectations. The chamber 2A may be large enough to provide room for bullets accumulating during several months or during an entire year of target practice so that the liquid must Ibe evacuated at infrequent intervals, for example, once in a year. Heretofore known bullet trapping assemblies whose bullet traps are filled with sand must ibe shut down four to six times per year, and each such shutdown lasts for about three weeks so that the shooting range using such conventional assemblies is closed during one third of each year. The casing 2 of our invention can be emptied, cleaned and refilled with a fresh supply of liquid within less than 48 hours, i.e., the assembly shown in FIGS. 1 and 2 can be used practically all year around. The construction and maintenance of any reasonably large shooting range or target practice range invariably involves very high costs and, therefore, the possibility of utilizing the bullet trapping assemblies of a shooting range all year around brings about unexpectedly high savings in money and manpower. The savings achieved with the improved bullet trapping assembly are exceptionally high and the cleaning of its casing 2 can be entrusted to a few persons without necessitating the use of any complicated and costly special equipment. As stated before, the cost involved in the m-aintenance of our assembly is negligible, and this is attributable (at least to a certain extent) to the fact that each bullet striking against the underside of the panel or liner 5 invariably rebounds into the supply of liquid 3 so that it cannot damage the bottom wall 2b or the upstanding walls of the casing, Repairs are infrequent and, when necessary, are not due to richocheting of bullets.

We rnade the suprising discovery that a panel or liner which is produced by compound casting and which is installed in a manner as shown in FIG. 2 will have a life expectancy which exceeds several times the life expectancy of other types of metallic liners. Even bullets tired from large-caliber rifles and using ammunition of high piercing power cannot penetrate the panel and each such bullet is properly defiected to descend into the body of liquid. Conventional hard steel plates having the same thickness as a plate of the type shown in FIGS. 3 or 4 will be destroyed after short periods of use. The durability of a panel consisting of compound steel is attributable to the fact that its hard lower layer a can be made much harder than a steel plate which is hardened in accordance with other methods and that such hardening of the layer a can be accomplished without risking the formation of cracks because the lower layer a is backed up by a relatively soft layer b. The aforementioned relatively thick intermediate zone between the softer layer b and each outer layer a also contributes to greater resistance of the panel. Such intermediate zone whose hardness varies gradually also prevents splitting of the compound panel, i.e., it prevents separation of the adjoining layers.

As a rule, a bulletproof panel must have a hardness of at least 600 HV. If such hardness is achieved by using a steel panel of uniform composition from one side to the other side thereof, the material of the panel is highly sensitive and overly brittle. On the other hand, if the material of the panel 5 were too soft, the bullets striking against its underside would form grooves, depressions and other unevennesses which would invariably lead to uncontrolled ricocheting of subsequently tired bullets with potential damage to the casing and danger to persons nearby.

At this time, we prefer to make the panel 5 of a material which is produced in a manner as described in con .nec-tion with. FIG. 4 and which. will not buckle during l'5 hardening due to different expansion coeliicients of its layers.

In many heretofore known bullet trapping assemblies, the chamber behind the target is filled with sand. Whenever a bullet pierces the target and penetrates into the body of sand, it produces a dust cloud which penetrates through or around the target and is likely to obscure the vision of participants in target practice. The size of the dust cloud depends on the caliber of the bullet and on the condition of the sand trap. In many instances, the

dust clouds are dense and large enough to necessitate length interruptions in target practice. Furthermore, if a bullet happens to strike a bullet which is already lodged in the body of sand, it will richochet lback through the target to endanger the Ipersons using the shooting range and/or to cause considerable damage to the casing.

As mentioned hereinbefore, such conventional bullet trapping assemblies must be shut down for lengthy intervals and at least four times per year so that their operation is not very economical. The need for lengthy shutdowns for the purpose of cleaning will be readily appreciated by bearing in mind that a sand trap may contain several hundred cubic meters of sand so that the evacuation, sifting and refilling of sand invariably requires several weeks. Also, the collection of bullets is more difficult than in the bullet trapping assembly of our invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various yapplications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is:

1. A bullet trapping assembly, comprising a casing delining a chamber containing a supply of liquid lling said chamber to a level below .the line of fire, said chamber having a front opening for entry of bullets and said casing having a downwardly inclined top wall extending rearwardly of said front opening and making an acute angle with the line of fire so that a bullet penetrating .through said front opening rebounds n said top wall and enters said supply of liquid, said top wall comprising a panel formed by at least one steel plate of .the type formed by compound casting and having at least one relatively hard steel layer and a relatively soft but tough steel layer and an intermediate zone between said layers whose hardness varies gradually between that of said two layers, said hard layer forming the outer layer of said panel exposed Ito said bullets.

2. A bullet trapping assembly as set forth in claim 1, wherein said casing comprises a bottom wall provided with a depression arranged to accommodate bullets which drop onto said bottom wall.

3. A bullet trapping assembly as set forth in claim 2, wherein said bottom wall is inclined downwardly toward said depression so that at least some bullets accumulating on said bottom wall tend to advance toward and into such depression.

4. A bullet trapping assembly as set forth iu claim 2, further comprising a receptacle removably accommodated in said depression to collect the bullets and to facilitate the evacuation of such bullets from said chamber.

5. A bullet trapping assembly as set forth in claim 1, further comprising a firing tunnel extending forwardly of said front opening and deformable compensator means located between said tunnel and said casing in the region of said front opening to compensate for different expansion of the materials of which said tunnel and the adjoining portion of the casing consist.

6. A bullet trapping assembly as set forth in claim 1, wherein said top wall further comprises a roof layer of concrete and said panel is secured at the underside of said roof layer.

7. A bullet trapping assembly as set forth in claim 1, wherein said steel plate includes a second hard outer steel layer and said relatively soft but tough steel layer is sandwiched therebetween and an additional intermediate zone between said soft layer and said second outer layer having a hardness which varies gradually between that of the layers adjacent thereto.

References Cited UNITED STATES PATENTS 1,294,407 2/ 1919 Coryell 273-l02.4 X 2,249,629 7/ 1941 Hopkins 29--l96.1 2,342,104 2/ 1944 Holt 29-196.l X 2,356,992 8/ 1944 Gilson 273-102.4 X 2,393,332 1/1946 Metzner 273-102 2,518,445 8/1950 Benson 273-1024 X 2,518,446 8/1950 lBenson 273-1024 X 2,631,454 3/1953 Shepard et al 73-167 2,812,660 11/1957 Marden et al. 73-167 2,813,422 11/1957 Schuessler 73--167 3,217,534 11/1965 Bingham et al. 73-167 415,174 11/1889 McCarty 249-62 1,710,931 4/ 1929 Klein 249-62 2,474,682 6/ 1949 Liebowitz 29-1961 3,237,908 3/ 1966 Harnisch et al. 164-76 FOREIGN PATENTS 316,195 2/1918 Germany.

12,377 5/ 1914 Great Britain.

ANTON O. OECHSLE, Primary Examiner. M. R. PAGE, Assistant Examiner.

U.S. Cl. X.R. 29-196.1