Abstract
Method of fabricating a dummy practice ammunition round to dynamically match behavior of an existing live ammunition round during manually cycling of the action, or other demonstration. A dummy practice ammunition round of identical contour is formed, having a center of gravity (mass) in the same position as on the existing live ammunition round. Weight is matched by removing or omitting material through coring into the case head of the round or by hollowing it out.
Claims
1. A method of fabricating and machining a dummy practice ammunition round to dynamically match behavior of an existing ammunition round during manually cycling of the action said existing ammunition round having a known outside contour, a known weight (W1), a known longitudinal axis, known case head, and a known center of gravity, wherein the method comprises the steps of: forming a dummy practice ammunition round of uniform density material, the dummy practice ammunition round having the same outer contour as the existing ammunition round, the dummy practice ammunition round having a weight (W2) which is greater than the known weight (W1) of the existing ammunition round, and removing material by coring, through the case head of the dummy practice ammunition round, a first symmetrical hollow cylinder (V1) at diameter (D1) and at a length (L1) which ends at a center of gravity, and then, starting at said center of gravity, coring out a second symmetrical hollow cylinder (V2) at diameter (D2) for a length of (L2), and; wherein the volume of hollow cylinder (V1) equals the volume of hollow cylinder (V2), and wherein the weight of the removed hollow cylinder (V1) plus the weight of the removed hollow cylinder (V2) together reduce the weight (W2) of the dummy practice ammunition round to equal the known weight (W1) of the existing ammunition round, and furthermore the final center of gravity of the dummy practice ammunition round is in the same location as the known center of gravity on the existing ammunition round.
2. The method of claim 1 where the dummy practice ammunition round has a smooth contour.
3. The method of claim 1 where the dummy practice ammunition round has flutes.
4. The method of claim 1 where the dummy practice ammunition round is made of a material which includes brass, steel, aluminum or some other material.
5. The method of claim 1, comprising filling the cored hole with plastic, epoxy resin, polymer, or other materials to dampen the movement of a firing pin and to prevent nesting of rounds within one another and to prevent debris from entering the dummy ammunition round.
6. The method of claim 1 where a bullet can screw into the case to simulate various cartridges.
7. The method of claim 1 where the coring is done on a screw machine or other types of machine tools.
8. The method of claim 1 where the processing of the dummy rounds is performed using 3D printing.
9. The method of claim 1 where the coring is done by hand.
Description
LIST OF DRAWINGS
(1) FIG. 1 shows a given live ammunition round the behavior of which is to be simulated by a dummy practice ammunition round, according to this invention.
(2) FIG. 2 shows a solid material, dummy practice ammunition round used for simulating the performance of the existing live ammunition round of FIG. 1, according to this invention.
(3) FIG. 3 shows the dummy practice ammunition round of FIG. 2, having volumes V1 and V2 of material removed or optimized therefrom, to simulate the weight and center gravity (mass) of the given existing live ammunition round, according to this invention.
(4) FIG. 4 illustrates a photo of a dummy practice round which has material removed or omitted from it in two cylindrical pockets in accordance with FIG. 3, according to this invention.
(5) FIG. 5 illustrates a photo of the exterior of a dummy practice round in accordance with this invention which round includes longitudinal flutes around the exterior thereof.
(6) FIG. 6 shows a side plan view of a known 7.62×54R nonstandard ammunition round according to this invention, for which a simulation dummy round is sought to be produced.
(7) FIG. 7 shows a cut-away view of a representative piece of inert ammunition used to create a dummy practice round in accordance with this invention.
(8) FIG. 8 shows another method of coring out coaxial cylindrical areas, to remove weight from the ammunition round.
(9) FIG. 9 shows a cross sectional view of the ammunition round, with an angular front shape conical portion in the foremost coaxial cylindrical cored out area.
DETAILED DESCRIPTION
(10) FIG. 1 shows a hypothetical ammunition round 100 to be simulated. Round 100 may be a NATO standard fully loaded cartridge or it may be a non-standard cartridge for simulation purposes. Round 100 is generally tubular shaped cross sectionally; it has a defined longitudinal axis 108, a defined front projectile 102, defined front most point 109, a defined case head 106, a given weight W1, and a defined center of gravity (mass) point 105. The center of gravity (mass) is a hypothetical point at which the round is equally balanced in all directions. If round 100 represents a standard model ammunition, the fully loaded weight, center of gravity (mass) and exact outside shape and dimensions are all known. If round 100 represents a nonstandard ammunition round, then these features could be determined empirically. In the case of a dummy round 200, 300 being produced in accordance to this invention, whether blank or processed according to the teachings of this invention, it will be presumed to be started of a solid material throughout of uniform density 215. It may be of aluminum, steel, brass, or other materials. The blank dummy round may be provided having a smooth outer contour as in FIG. 4 or a fluted outer contour as in FIG. 5 to better identify it as a dummy round (or perhaps also as an expedient to also remove weight). Successful dummy blanks have been recently made and tested for a nonstandard ammunition round 7.62×54 R (see FIGS. 6 and 7), 7.62×39, 9×18, 12.7×108. Furthermore. NATO standard 5.56×45, 7.62×51 and 0.50 Cal BMG, rounds have been made having the same weight as live rounds. These have all received favorable comments from field technicians or design engineers. The blank dummy round according to this invention, before processing such as in FIG. 2, starts out being made at weight W2, heavier than the (known) weight W1 of the standard (or nonstandard) model ammunition it is going to simulate, but having the same exact outer contours within specification thereof. As will be seen, for example in FIG. 3, pockets of material V1 and V2 will be removed (cored out) until the remaining weight of the dummy round blank then equals the weight within given tolerance of the fully loaded standard (or nonstandard) model ammunition it is going to be used to simulate. Moreover, and this is an important feature of this invention, the center of gravity (mass) in this processed dummy round blank 205, ideally still has to be at the same location 105 within given tolerance just as in the fully loaded standard (or non standard) model ammunition it is going to be used to simulate. Creating the necessary sizing in the pockets of removed or omitted material V1 and V2 to accomplish the duplication of final weight plus duplicated location of the center of gravity (mass) 105, represents a great accomplishment of this invention. Of note, the center of gravity (mass) 205 on the processed dummy round would tend to move as material is removed at V1 and V2. So, removal of material from the cylindrical pockets to lessen the weight of the processed dummy round may work at cross purposes to ensuring that the center of gravity (mass) 205 of the processed dummy round is at the desired location 105. As a practical expedient, the parameters L1, D1, L2, D2 may be designed by an operator without the aid of a computer, and the dummy round blank simply cored out, symmetrically along the defined longitudinal axis to get the weight of the dummy round down to the required amount, without taking into consideration if center of gravity (mass) 205 of the dummy round is precisely at location 105. That is to say, the imperfection of the dummy round center of gravity (mass) might conceivably be tolerated because the processed dummy round will function satisfactorily enough compared to other current dummy round alternatives. Moreover, the operator may have saved a table of acceptable range values for parameters L1, D1, L2, D2 from previous successful simulations of known ammunition model numbers and sizes, whereas such could be simply looked up in the table and the dummy round cored out manually. Such could also be saved in and looked up in, a computer as well, if desired. However, this invention seeks also to calculate algebraically the needed parameters of the cylindrical cutouts V1 and V2, from D1, L1, D2 and L2 in a hypothetical to serve as an example. In the example of FIG. 3, length L1 is chosen so it ends at point 205 equal to point 105, so the two volumes V1 and V2 can be placed back to back. Criteria 1: As seen in FIG. 3, to lower the final weight of this processed round to be equal to W1, then the total weight of removed volumes V1 plus V2 must be equal to W2−W1. The weights of either V1 and V2 can be known geometrically by density of the material, times Pi, times the length of a cylinder (L1 or L2), times the square of the diameter of the cylinder (D1 or D2), all the above divided by four. So as a first equation, (Density times Pi times L1 times the square of D1 all divided by 4)+(Density times Pi times L2 times the square of D2 all divided by 4)=W2−W1. Criteria 2: To keep the center of gravity (mass) 205 from moving from its position, and so it will still be the same place as 105 was, then the weight of volumes V1 and V2 should be kept equal in amount to one another. Therefore: (Density times Pi times L1 times the square of D1 all divided by 4)=(Density times Pi times L2 times the square of D2 all divided by 4). This reduces to L1 times the square of D1=L2 times the square of D2. If one assumed the first cylinder parameters for L1 and D1 as a starting point in an iteration process, then the values of L2 and D2 can certainly be calculated through solution of these simultaneous equations, or otherwise, so that both criteria are met. Such simultaneous equations could be solved to determine the precise parameters for cutting out the material, or these calculations could in theory actually be automated on a computer. To ensure that the center of gravity (mass) of the processed dummy round also to be at the precise location 105 as what the standard fully loaded cartridge 100 would have had, another way is there might also be used an iterative process, which may be done by computer, to try out proposed quantities of the various parameters here, L1, L2, D1, D2 to accomplish this. The iterative process could perhaps begin with W1, W2, material density as knowns and only one or more of L1, L2, D1, D2 as starting amounts while varying all the other parameters in the computer iteratively, to find good matches and good ranges for the parameters to make allowances for sufficient wall thickness for structural integrity. There may be more than one set of matches for L2 and D2 for instance, or conceivably if no matches are possible at all theoretically, then the computer might so inform the operator of that outcome. The pockets may be made of various shapes theoretically, but here as an example they were shown as two symmetrical hollow cylindrical cavities lying coaxially along the defined longitudinal axis 108, 208. For practical purposes of precision machining out of the material to make these cavities hollow, the first cavity V1 is made of wider diameter than the second cavity V2. This is also partly due to needing room to insert a cutting tool, and also through the first cylinder so as to be able to reach the second cylinder location to do some coring. Then, the second cavity V2 could be cored out as to diameter D2 and depth L2, as for example, on a Tsugami SS327-5AX screw machine device, to get a final, processed dummy round. As mentioned, other symmetrical shapes could be explored for fabricating the pockets of removed material. In this fashion, precision dummy rounds of superior quality can be produced for numerous standard/nonstandard fully loaded ammunition cartridges. This would certainly facilitate mass production techniques for these dummy practice rounds.
(11) An alternative way to manufacture would be to utilize 3D printing enabling alternative methods of design that cannot be ascertained with conventional machining methods to include hollowing out the cavity having a smaller primer pocket which wouldn't be feasible for conventional machining.
(12) Another method wherein the processing of the dummy rounds may be performed is by the 3D printing of the ammunition rounds. The ammunition round may be made up of multiple materials to include but not be limited to, filling the core hole with plastic epoxy, resin, polymer, or other materials to dampen/cushion the movement of the firing pin and to prevent nesting of rounds within one another and to prevent debris from entering. The bullets may be made so they can screw in/out of the case to simulate various cartridges in one design. FIG. 8 here shows another method of coring out coaxial cylindrical areas, to remove weight from the ammunition round. FIG. 9 here shows a cross sectional view of the ammunition round, with a front conical shaped portion in the foremost coaxial cylindrical cored out area.
(13) While the invention may have been described with reference to certain embodiments, numerous changes, alterations and modifications to the described embodiments are possible without departing from the spirit and scope of the invention as defined in the appended claims, and equivalents thereof.
