CAVITATION CORE OF A FIREARM PROJECTILE

Abstract

The invention relates to firearm projectiles, primarily for destroying underwater targets in the case of underwater or air-to-water fire. A cavitation core of a firearm projectile results in an increase in target destruction efficiency by virtue of approximating the contour (R) of the cavitation core to the contour of the cavity (W) in the water, increasing the mass of the core and allowing loss of cavitation stability and rolling in a non-uniform (heterogeneous) and compressible water-containing medium.

Claims

1. A cavitating core of firearm ammunition comprising, at least: a head portion conjugated with a secant nose surface having a cavitating edge, a central portion, and an aft portion with a gliding surface designed to stabilize the cavitating core in a cavity due to one-sided periodic wetting and gliding along the cavity contour (W), wherein the cavitating core caliber (D) is defined by the largest diameter of the circle circumscribing the cross-section of the gliding surface, wherein in the plane of the cavitating core axial longitudinal section, the current diameter (D.sub.X) of the enveloping contour line (R) from the cavitating edge to the cavitating core caliber (D) is limited by the equation:
D.sub.X=d×[1+(L.sub.X/d)×2π×sin φ/π)].sup.N, wherein: D.sub.X—is the current diameter of the enveloping contour line (R) on the current length (L.sub.X) from the cavitating edge to the cavitating core caliber (D) (in mm); d—is the diameter of the vaitating edge (in mm); L.sub.X—is the current length from the cavitating edfe to the cavitating core caliber (D) (in mm); φ=60° . . . 180°—is the apex angle of the tangents to the secant nasal surface at the points of its conjugation with the cavitating edge measured from the side of the head portion; N=0.25 . . . 0.40—is the cavitating core volume factor, wherein the cavitating core caliber (D) is equal to the current diameter (D.sub.X) of the enveloping contour (R) when L.sub.X=L, where (L) is the length from the cavitating edge to the cavitating core caliber (D), and the center of mass of the cavitating core is located at the length X≥0.3 D in front of the leading edge of the gliding surface at the length (L).

2. The cavitating core in accordance with claim 1, wherein the secant nasal surface is made in the form chosen from the group including: a flat face, a cone, a cone with a rounded top, a truncated cone, or a truncated cone with a rounded edge of a smaller base.

3. The cavitating core in accordance with claim 1, wherein a narrow circular groove, the smallest diameter of which equals to 1.3-1.8 of the diameter (d) of the cavitating edge is made in the head portion.

4. The cavitating core in accordance with claim 1, wherein the aft portion is made in the form of a multi-blade tail fin stabilizer and is equipped with a cylindrical tail section designed for fastening the cavitating core in an ammunition.

5. The cavitating core in accordance with claim 1, wherein the aft portion is made in the form of a multi-blade tail fin stabilizer and is provided with a possibility of free rotation around the longitudinal axis of the cavitating core.

6. The cavitating core in accordance with claim 1, wherein the head portion and central portion are equipped with a protective cap that is discarded during the cavitating core acceleration in the barrel.

7. The cavitating core in accordance with claim 1, wherein it is equipped with a discarding sabot designed to lead the cavitating core during acceleration in the barrel and to stabilize at the flight in the air that is discarded when the cavitating core enters the water.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The invention is explained in more detail with the reference to specific embodiments that in no way reduce the volume of claims and are only intended for better understanding of the invention by one of skill in the art, In the description of specific embodiments of the invention there are references to the accompanying drawings that show the following:

[0041] FIG. 1 shows the first example of the invention embodiment in a cavitating core of .223 (5.56×54.45 mm) ammunition during its movement in a cavity formed in the water;

[0042] FIG. 2 shows the second example of the invention embodiment in a cavitating core, which is fastened in .223 (5.56×45 mm) ammunition;

[0043] FIG. 3 shows the photo of a block of ballistic gelatin with a shot hole from the cavitating core of the given invention that is shown in FIG. 1; [0044] FIG. 4 shows the photo of a block of ballistic gelatin with a shot hole from the cavitating core “prototype” of .223 (5.56×45 mm) ammunition;

[0045] FIG. 5 shows the third example of the invention embodiment in a cavitating core of 12th gauge shotgun ammunition during its movement in a cavity formed in the water; and,

[0046] FIG. 6 shows the fourth example of the invention embodiment in a cavitating core, which is fastened in 12th gauge shotgun ammunition (12/70).

DETAILED DESCRIPTION

[0047] Cavitating cores of firearm ammunition according to the invention can be used for underwater hunting and for protection against attacks by predators in the water when firing from existing and perspective small arms and hunting guns, as well as when using the device for underwater firing from small arms according patent RU 2 733 018 C1 of 28 Sep. 2020 and publication of international application WO 2021/167489 A1 of 26 Aug. 2021. Ammunition with cavitating core can be included in the allowance of ammunition of combat swimmers, marines, coast guards, ship staff and naval aviation crews.

[0048] Ammunition with cavitating core can be used to defend sea and coastal objects from attacks by underwater, surface and air attack weapons when firing from existing and prospective machine guns and cannon armaments of aviation, ships and submarines, as well as when using the device for underwater firing from a firearm according patents RU 2 498 189 C2 of 10 Nov. 2013 and U.S. Pat. No. 8,919,020 B2 of 30Dec. 2014 and EP 2 690 390 B1 of 10.08.2016, as well as when using the recoilless underwater firearm according patents RU 2 651 318 C2 of 19 Apr. 2018 and U.S. Pat. No. 10,591,232 B2 of 17 Mar. 2020 and EP 3 431 915 B1 of 20 Oct. 2021.

[0049] The invention can be used in designs of jet weapons intended for flight in the air and/or cavitation movement in the water.

[0050] FIG. 1 shows a schematic view of a cavitating core (G.sub.1) of .223 (5.56×45 mm) ammunition after a shot from a rifled barrel and gliding along a cavity contour OM formed in the water. The cavitating core (G.sub.1) includes: a head portion 1 conjugated along a cavitating edge 2 with a diameter (d) with a secant nasal surface 3, made in the form of a cone with a rounded top, where an apex angle of the tangents to the secant nasal surface 3 at the points of its conjugation with the cavitating edge 2 is φ=90°, a central portion 4 and an aft portion 5 with a gliding surface 6.

[0051] In the plane of the axial longitudinal section of the cavitating core (G.sub.1), the current diameter (D.sub.X) of the enveloping contour line (R) of its cross-sections from the cavitating edge 2 to the leading edge of the gliding surface 6, located at the length (L), the diameter of which is equal to the cavitating core caliber (D), is limited by the equation:

D.sub.X=d×[1+(L.sub.X/d)×2π×sin φ/π].sup.N, wherein:

d=2.1 mm; φ=90°; π=3.14; N=0.3157 and D=D.sub.X=5.68 mm when L.sub.X=L=15.6 mm, where (L) is the length from the cavitating edge 2 to the cavitating core caliber (D).

[0052] The rounding of the top of the nasal surface 3 is made in the form of a spherical segment with the base diameter of 0.4 d for the correct formation of the cavity contour (W). The cavitating edge 2 has a cylindrical section 7, and the leading edges of the cylindrical sections 8 and 9 may coincide with the current diameters (D.sub.X1) and (D.sub.X2) of the enveloping contour line (R) at the current lengths L.sub.X1=3.0 mm and L.sub.X2=12.5 mm. These cylindrical sections 7, 8 and 9 allow precise control of the manufacture of their dimensions, which determine the operability of the cavitating core. Other outer surfaces of the head portion 1 and the central portion 4 are limited (slightly less) by the enveloping contour line (R), which simplifies their manufacture and control. The cylindrical sections 8 and 9, as well as the tapered circular groove 10 are intended for fastening a protective cap shown in FIG. 2.

[0053] The cavitating core (G.sub.1) contains a slug 12 pressed with its cylindrical portion 13 into a jacket 14, The mass of the cavitating core (G.sub.1) is 5.4 g when the slug 12 and its cylindrical portion 13 are made of high-density and high-strength material, namely, tungsten alloy with the density ρ=17.0 g/cm.sup.3 and the jacket 14 is made of easily deformable non-ferrous alloy, namely, of brass with the density ρ=8.4 g/cm.sup.3. The base pocket 15 in the jacket 14 shifts the center of mass of the cavitating core (G.sub.1) to the head by the length X=0.38 D from the leading edge of the gliding surface 6 located at the length (L), that complies with the conditions of this invention (X≥0.30) and provides rectilinear cavitation movement in the water. Herewith, the dimensions of the cylindrical portion 13 of the slug 12 and the sizes of the base pocket 15 provide the possibility of varying the location of the center of mass.

[0054] The length of the cavitating core (G.sub.1) equals to 4.6D and its stabilization in the air is provided by spin when fired from a standard 5.56 mm rifled barrel with the twist rate of 7″ (178 mm), and at a shot the rifling grooves 11 from the rifled barrel are formed on the outer surfaces of (D) and (D.sub.1) diameters. In the water, the cavitating core (G.sub.1) touches the cavity contour (W) by its gliding surface 6 with the rifling grooves 11, and the diameter (D.sub.1) does not touch the cavity contour (W). At the same time, the diameter (01) can be less than the cavitating core caliber (D), for example, D.sub.1=0.995 D for better fastening of the cavitating core in the neck of the cartridge case, as it is shown in FIG. 2. Besides, the diameter (D.sub.1) can be equal to the cavitating core caliber (D), for example, D.sub.1=D to simplify the cavitating core manufacturing technology. Moreover, the diameter (D.sub.1) may exceed the cavitating core caliber (D), for example, D.sub.1=1.01 D when using the cavitating core design (G.sub.1) in ammunition of a recoilless firearm shown in FIG. 6. During the movement in the cavity formed in the water and gliding the surface 6 along the cavity contour (W), the maximum inclination angle (ω) of the cavitating core (G.sub.1) in the cavity is ω=4.0° with the maximal design gap δ.sub.L=2.18 mm at the length L=15.6 mm. At the same time, the minimum design gaps δ.sub.1=0.35 mm and δ.sub.2=0.09 mm are formed between the cavity contour (W) and the leading edges of the cylindrical sections 8 and 9 at the lengths L.sub.X1=3.0 mm and L.sub.X2=12.5 mm, respectively.

[0055] During the movement in heterogeneous and compressible aqueous-containing medium, the depth of wetting of the gliding surface 6 beyond the cavity contour (W) increases and the inclination angle (ω) of the cavitating core (G.sub.1) increases as well. This leads to the disappearance of the gap (δ.sub.2) and flushing of the surface of the cylindrical section 9 in the zone of the center of gravity of the cavitating core, which causes a change in its trajectory. At the same time, a decrease in the gap (δ.sub.1) and flushing of the surface 8 by the aqueous-containing medium particles makes the cavitating core (G.sub.1) lose its cavitation stability, overturn, an increase in the contact area with the object of the hunt and sharp braking with the transfer of all energy to the hunted object, which significantly increases its stopping power in comparison with the cavitating cores “prototype” and “analog”.

[0056] FIG. 2 shows a schematic view of a fragment of .223 (5.56×45 mm) ammunition with a fastened cavitating core (G.sub.2). The ammunition includes: a brass cartridge case 22 with a primer and a propellant charge 21, in the neck of which the cavitating core (G.sub.2) with a protective cap 22 is fastened. The dimensions and designation of the outer surfaces of the cavitating core (G.sub.2) are equal to the dimensions of the cavitating core (G.sub.1). The mass of the cavitating core (G.sub.2) is 3.1 g when it is made of easily deformable non-ferrous alloy, namely, of bronze with the density ρ=8.8 g/cm.sup.3, The base pocket 15 allows to place a part of the propellant charge 21 in it and shifts the center of mass of the cavitating core to the head by the length X=0.35 D from the leading edge of the gliding surface 6 located at the length (L). That meets the terms of this invention (X≥0.30) and provides rectilinear cavitation movement in the water.

[0057] A protective cap 22 is pressed onto the cylindrical sections 8 and 9 and fixed in a conical circular groove 10. The protective cap 22 has a mass of 0.12 g when made of plastic of a PA-6 type with the density ρ=1.12 . . . 1.15 g/cm.sup.3 and tensile strength Rm=65 . . . 70 MPa and is designed to protect the nasal surface 3 with the cavitating edge 2 from damage during transportation, ammunition assembling and using ammunition in weapons, as well as to ensure better ammunition sealing. The diameter D.sub.232 1.005 D ensures a tighter fixation of the plastic cap 22 in the neck 23 of the cartridge case 20. The length of .223 (5.56×45 mm) ammunition with the cavitating core of the given invention is equal to the length of standard .223 (5.56×45 mm) ammunition for a possibility of using it in the existing firearms.

[0058] During a shot and accelerating the cavitating core (G.sub.2) or (G.sub.1) with the plastic cap 22 in the barrel bore, a propellant gas flows through a narrow longitudinal groove 24 and fills cavities 25 and 26 between the inner surface of the plastic cap and the outer surface of the head part of the cavitating core. The plastic cap 22 discards in the middle part or in muzzle part of the barrel bore from the pressure of the propellant gas accumulated in the cavities 25 and 26, and the cavitating core moving at this moment in the rifled barrel does not receive any initial disturbances from the discarding of the plastic cap.

[0059] Similarly, the plastic cap 22 discards from the cavitating core at underwater firing from a wet firearm, which is accompanied by the expulsion of the water by the propellant gas from the barrel. Moreover, for underwater firing, specially loaded universal ammunition with a reduced mass of the propellant charge is used, which provides an allowable pressure during an underwater shot accompanied by pushing water out of the barrel. At the same time, the operability of standard assault rifles “HK 416”, “HK SL8”, “LAT-Piston”, “Galil ACE” and “FN SCAR-L” was experimentally determined during automatic underwater firing with universal .223 (5.56×45 mm) ammunition with cavitating core of the given invention and with cavitating cores “prototype”.

[0060] The cavitating core (G.sub.2) has a lower mass and effective underwater firing range than the cavitating core (G.sub.1), but it can be used for sports firing in “Aqua Shooting Range” according patents RU 2 316 712 C2 of 10 Oct. 2008 and U.S. Pat. No. 7,942,420 B2 of 17 May 2011 and EP 1 884 736 B1 of 29 May 2013. At the same time, the cavitating core (G.sub.2) loses its cavitation stability and overturns when penetrating into a block of ballistic gelatin, similar to the cavitating core (G.sub.1). When firing from the air into the water with a muzzle velocity of V.sub.0=950 m/s, and when underwater firing from wet firearm with a muzzle velocity of V.sub.0=710 m/s, the cavitating core (G.sub.2) has a velocity of V=220 m/s and energy of E=75 Jules at an underwater range S=5 m and S=4 m, respectively. Therefore, .223 (5.56×45 mm) ammunition with the cavitating core (G.sub.2) may be used to hunt fish weighing up to 40 kg up to S=4 . . . 5 m underwater range.

[0061] When firing in the air with a muzzle velocity V.sub.0=950 m/s, the cavitating core (G.sub.2) has a velocity and energy: V.sub.100=800 m/s and E.sub.100=990 Jules, V.sub.200=680 m/s and E.sub.200=720 Jules, at 100 m and 200 m range, respectively. Improvement of ballistic parameters can be provided by reducing the diameter (d) of the cavitating edge 2 and the area (S.sub.N) of the nasal surface 3 with an increase in the angle (φ) to maintain the parameter (c.sub.X×d) and the cavity contour (W). For example, the cavitating cores (G.sub.1) and (G.sub.2) have the area of the nasal surface 3, taking into account the rounded top, is S.sub.N=4.60 mm.sup.2 at φ=90° and d=2.1 mm, and at dimensions of φ=180° and d=1.7 mm, the area of the nasal surface will decrease by 100% (S.sub.N=2.27 mm.sup.2), while the parameter (c.sub.X×d) and the cavity contour (W) will not change, but the wave resistance of the nasal surface in the air will decrease.

[0062] The cavitating core (G.sub.2) can be made of an easily deformable material with strength parameters equivalent to low carbon steel or non-ferrous alloys such as copper, tombac or brass, and filled with a high-density material with density parameters equivalent to tungsten or lead based alloys. The mass of the cavitating core (G.sub.2) can be increased to 3.6 g by making the base pocket 15 to the cylindrical section 8 and filling this volume with lead with the density ρ=11.3 g/cm.sup.3 while maintaining the unfilled part of the base pocket 15 to ensure the center of mass along the length X≥0.3 D from the leading edge of the gliding surface 6. This will improve the ballistic and hydrodynamic parameters of the cavitating core (G.sub.2) by increasing its mass. Moreover, in the part of the base pocket 15 not filled with lead, a tracer with the density ρ=1.6 . . . 1.8 g/cm.sup.3 can be installed, which can increase the effectiveness of firing in the water and in the air at a moving target.

[0063] Comparison of the enveloping contour (R) of the cavitating core (G.sub.1 or G.sub.2) of this invention and it “analog” shows that the enveloping contour (R) of the “analog” is limited by the diameter 0.4 D =2.27 mm at the length of 0.4 D. But, in the cavitating core (G.sub.1 or G.sub.2) at the length L.sub.X=0.4D, the enveloping contour (R) is limited by the diameter D.sub.X=3.05 mm, and is 34% bigger than the diameter of the enveloping contour (R) of the “analog”. This shows that the enveloping contour (R) of the given invention is closer to the cavity contour (W) than the enveloping contour (R) of the “analog”.

[0064] Comparative calculation of the enveloping contour (R) of the cavitating core (G.sub.1) or (G.sub.2) using the “prototype” equation:

D.sub.X=d×[1+(L.sub.X/d)×(2 sin φ/π).sup.1/N].sup.N

shows that at the sizes: d=2.10 mm, φ=90° and N=0.484 between the cavity contour (W) and caliber D=5.68 mm of the cavitating core “prototype”, the design gap δ.sub.L=2.18 mm and the maximum inclination angle ω=4.0° at the length L=15.6 mm are formed. And the minimum design gaps are δ.sub.1=0.65 mm and δ.sup.2=0.15 mm that can be formed between the enveloping contour (R) and the cavity contour (W) at the lengths L.sub.X1=3.0 mm and L.sub.X2=12.5 mm, respectively. This calculation shows that in the cavitating core “prototype” the gaps (δ.sub.1) and (δ.sub.2) are 60% larger than the gaps (δ.sub.1) and (δ.sub.2) in the given invention. This provides stable cavitation movement of the cavitating core “prototype” in the cavity formed in the water and in a heterogeneous and compressible aqueous-containing medium.

[0065] Comparative firing with .223 (5.56×45 mm) ammunition with the cavitating core (G.sub.1) of the given invention with the mass of 5.4 g and with cavitating core “prototype” with the mass of 5.2 g into aqueous-containing targets at impact velocities in the interval from 250 m/s to 750 m/s confirmed differences in their stopping power features.

[0066] Firing into ballistic gelatin blocks with sizes of 200×200×500 mm, containing about 80-90% of the water showed the following: [0067] the cavitating core (G.sub.1) of the given invention forms a curved hole with a volumetric cavity from its overturning due to losing of cavitation stability and is stopped in the ballistic gelatin block at a length of 0.35-0.45 m, as shown in FIG. 3; [0068] the cavitating core “prototype” pierces two ballistic gelatin blocks with a total length of one meter and continues its flight, and a through hole with a diameter of 8-10 mm is formed in the ballistic gelatin blocks, as shown in FIG. 4.

[0069] FIG. 3 shows the photo of a ballistic gelatin block with sizes of 200×200×500 mm with the curved hole (A) and the volumetric cavity (B) after firing with .223 (5.56×45 mm) ammunition with the cavitating core (G.sub.1) with the mass of 5.4 g at the impact velocity of V=518 m/s, where the arrow (V) indicates the direction of movement of the cavitating core.

[0070] FIG. 4 shows the photo of a ballistic gelatin block with sizes of 200×200×500 mm with the through hole with a diameter of 8-10 mm (C) after a shot with .223 (5.56×45 mm) ammunition with the cavitating core “prototype” with the mass of 5.2 g at the impact velocity of V=526 m/s, where the arrow (V) indicates the direction of movement of the cavitating core, while the asymmetry of the through-hole channel (C) shows a heterogeneous composition of the ballistic gelatin.

[0071] Firing into ripe watermelons containing 80-90% of water showed the following: [0072] the cavitating core (G.sub.1) of the given invention loses cavitation stability and overturns in the pulp of the watermelon and breaks the watermelon at many fragments, while the pulp of the watermelon in these fragments retains its taste and is suitable for eating; [0073] the cavitating core “prototype” makes a through hole in the watermelon and continues its flight without loss of cavitation stability, while all the watermelon pulp turns into a mucous mass due the hydraulic effect from the formed cavity and is not suitable for eating.

[0074] These examples show that the given invention increases the efficiency of the cavitating core by providing a possibility of losing its cavitation stability in an inhomogeneous (heterogeneous) and compressible aqueous-containing medium.

[0075] An example of increased cavitation stability of a cavitating core “prototype” of brass with the mass of 8.0 g for .308 (7.62×51 mm) ammunition, which at impact velocity about 800 ,/s, does not change its trajectory at walls piercing with cavity formation in twelve plastic containers filled with water, is shown on the website:

www.guns.com/news/2012/08/28/pnw-arms-supercavitating-underwater-ammo

[0076] Another example of increased cavitation stability of a cavitating core “prototype” with the mass of 15.9 g for .308 (7.62×51 mm) ammunition, which at impact velocity about 550 m/s penetrates with cavity formation into a ballistic gel (gelatin blocks) four meters long and a watermelon without any deformation of these targets is shown on the websites:

www.youtube.com/watch?v=U2zfy75-f_k
en.topwar.ru/165443-pulja-v-puzyre-su perkavitacionnye-boepripasy-iz-norvegii.html
gunportal.com.ua/10587/2019105/26/norvezhcy-poxyastalis-kavitiruyushhimi-pulyami/

[0077] FIG. 5 shows a schematic view of a cavitating core (G.sub.3) of 12th gauge shotgun ammunition (12/70) after a shot and gliding along the cavity contour (W) formed in the water. The cavitating core (G.sub.3) includes: a head portion 1 conjugated along a cavitating edge 2 with a diameter (d) with a secant nasal surface 3, made in the form of a truncated cone, where an apex angle of the tangents to the secant nasal surface 3 at the points of its conjugation with the cavitating edge 2 is φ=120°, a central portion 4 and an aft portion 5 with a gliding surface 6. The aft portion 5 is made in the form of a bushing 31 with a six-blade tail fin stabilizer 32 with the gliding surface 6 mounted for free rotation on a threaded pin 33 and fixed by a disk 34, which has the form of a cylindrical tail section with a gliding surface 6.

[0078] In the plane of the axial longitudinal section of the cavitating core (G.sub.3), a current diameter (D.sub.X) of the enveloping contour line (R) of its cross-sections from the cavitating edge 2 to the leading edge of the gliding surface 6 located at the length (L), the diameter of which is equal to the cavitating core caliber (D), is limited by the equation:

D.sub.X=d×[1+(L.sub.X/d)×2π×sin φ/π].sup.N, wherein:

d=3.15 mm; φ=120°; π=3.14; N=0.3847 and D=D.sub.X=18.5 mm when L.sub.X=L=80 mm, where (L) is the length from the cavitating edge 2 to the cavitating core caliber (D).

[0079] The diameter of the smaller base of the truncated cone of the nasal surface 3 is 0.4 d for the correct formation of the cavity contour (W). The cavitating edge 2 has a cylindrical section 7, and the leading edges of the cylindrical sections 8, 9 and the leading edge 35 of the tail fin stabilizer 32 may coincide with the current diameters (D.sub.X1, D.sub.X2 and D.sub.X3) of the enveloping contour line (R) at the current lengths L.sub.X1=6 mm, L.sub.X2=16 mm and L.sub.X3=60 mm. These cylindrical sections 7, 8 and 9 allow precise control of the manufacture of their dimensions, which determine the operability of the cavitating core.

[0080] Other outer surfaces of the head portion 1 are limited (slightly less) by the enveloping contour line (R), which simplifies their manufacture and control. The outer surface 36 of the blades of the tail fin stabilizer 32 from the leading edge 35 to the cavitating core caliber (D) is made in the form of a truncated cone, the bases of which coincide with the diameters (D.sub.X3 and D) of the enveloping contour line (R) at the lengths (L.sub.X3 and L). In the central portion 4, a thread 37 (M12×1.5) is made for fastening a discarding sabot, as shown in FIG. 6. Therefore, the outer surfaces of the cavitating core (G.sub.3) from the leading edge of the cylindrical section 9 to the leading edge 35 of the tail fin stabilizer 32 (from L.sub.X2 to L.sub.X3) are underestimated relative to the enveloping contour line (R), but it is a design feature of the cavitating core (G.sub.3).

[0081] The mass of the cavitating core (G.sub.3) is 75 g when the head portion 1, the central portion 4 with a threaded pin 33 and the bushing 31 with a six-blade tail fin stabilizer 32 are made of easily deformable non-ferrous alloy, namely, of brass with the density ρ=8.4 g/cm.sup.3, and the disk 34 is made of D16T type aluminum alloy with the density ρ=2.7 g/cm.sup.3 and tensile strength Rm=450 . . . 500 MPa. The center of mass of the cavitating core (G.sub.3) is located at the length X=1.60 D from the leading edge of the gliding surface 6 at the length (L), this fulfill the condition of this invention (X≥0.3 D) and provides rectilinear cavitation movement in the water.

[0082] The cavitating core (G.sub.3) has a length of 4.8 D and is stabilized in the air by the aerodynamic drag of the aft portion 5 when fired from a smooth or rifled barrel. Aerodynamic stabilization in the air is achieved by the six-blade tail fin stabilizer 32 with a blade thickness of 1.5 mm and a disk 34, which increases aerodynamic drag, but provides a rapid decrease in the angles of attack of the cavitating core after exiting the barrel and a sabot discarding, which is especially necessary when shooting from the air into the water from a short distance. In addition, the disk 34 may be designed for fastening the cavitating core (G.sub.3) in the cartridge case of ammunition (see FIG. 6) and sealing a propellant charge, and also for providing obturation of a propellant gas together with a sabot when the cavitating core accelerates in the barrel. The gliding surfaces 6 of the tail fin stabilizer 32 with the diameter (D) and the gliding surface 6 of the disc 34 with the diameter (D) may be calibrated together to eliminate their asymmetry. When fired from a rifled barrel, the head portion 1, the central portion 4 with the threaded pin 33 and the disc 34 will rotate, At the same time, the possibility of free rotation of the bushing 31 with the tail fin stabilizer 32 around the threaded pin 33 prevents its joint rotation with the head and central portions when fired from a rifled barrel, which reduces dispersion of cavitating cores in the air and in the water. The head portion 1 is provided with a narrow circular groove 38 with the smallest diameter d.sub.1=1.5 d and an edge 39, which is formed at the conjugation of the rear wall of the circular groove 38 with the outer surface of the head portion 1 of the cavitating core. This groove 38 allows the cavitating core to enter the water when firing at a low angle to the water surface by creating a temporary cavity by means of this edge 39. When the cavitating core enters the water at a small angle to the water surface and the nose surface of the head portion 1 is flushed up to the groove 38; at the same time the edge 39 creates a temporary increased cavity under the cavitating core, which prevents flushing of the rest of its surfaces. After the cavitating core is immersed into the water, the cavity is formed by the cavitating edge 2 with the diameter (d). Moreover, the narrow circular groove 38 increases the destructive power of the cavitating core. In case the head portion 1 is made of an easily deformable material (non-ferrous alloy or low-carbon steel), the nose of head portion 1 bends along the smallest diameter (d.sub.1) of the circular groove 38 when it hits a hard obstacle, for example, when it hits a bone tissue of the hunting object, This accelerates the loss of stability of the curved cavitating core in the soft tissues of the hunting object. In case the head portion 1 is made of a high-strength material (hardened steel or tungsten alloy), the nose of the head portion 1 breaks off along the smallest diameter (d.sub.1) of the circular groove 38 when the cavitating core hits a hard target that is located at a small angle to the firing line. At the same time, the edge 39 formed at the conjugation of the rear wall of the circular groove 38, the diameter of which is larger than the cavitating edge diameter (d), interacts with the target that excludes the cavitating core ricochet.

[0083] During the movement in the cavity formed in the water and gliding the surface 6 along the contour of the cavity (W), the maximum inclination angle (ω) of the cavitating core (G.sub.3) in the cavity is ω=0.8° with the maximal design gap δ.sub.L=2.30 mm at the length L=80 mm. At the same time, the minimum design gaps δ.sub.1=0.36 mm, δ.sub.232 0.15 mm and δ.sub.3=0.04 mm are formed between the cavity contour (W) and the leading edges of the cylindrical sections 8, 9 and the leading edge 35 of the tail fin stabilizer 32 at the lengths L.sub.X1=6 mm, L.sub.X2=16 mm and L.sub.X3=60 mm respectively. At the same time, in the case of an increase in angular vibrations of the heavy cavitating core (G.sub.3) in the cavity, there is a possibility of an inertial washing of the gliding surface 6 beyond the cavity contour (W) and the disappearance of the gap (δ.sub.3) with flushing of the outer surface 36 of the tail fin stabilizer 32 from the edge 35 to the core caliber (D). This increases the area of the gliding surface and provides additional stability of the cavitating core in the cavity, but cannot change its underwater trajectory, since in this case the center of mass will be located at the length X.sub.1=0.52 D from the leading edge of the gliding surface, which will start from the leading edge 35 of the tail fin stabilizer 32 at the length (L.sub.X3), that meets the terms of this invention (X≥0.3 D) and provides rectilinear cavitation movement in the water.

[0084] During the movement in a heterogeneous and compressible aqueous-containing medium, the depth of wetting of the gliding surface 6 and the outer surface 36 of the tail fin stabilizer 32 beyond the cavity contour increases, At the same time, the inclination angle (ω) of the cavitating core increases and the gap (δ.sub.2) that is less than the gap (δ.sub.1) disappears, and the flushing of the surface 9 with subsequent flushing of the thread 37 by the aqueous-containing medium particles makes the cavitating core (G.sub.3) lose its cavitation stability and start its overturn in the cavity. At the same time. the gap (δ.sub.1) disappears and the edge 39 forms an enlarged cavity, which contributes to the accelerated overturn of the heavy cavitating core (G.sub.3), an increase in the contact area with the object of the hunt and its and sharp braking with the transfer of all energy to the hunting object, which significantly increases its stopping power in comparison with the cavitating core “prototype”.

[0085] At a shot in the air or in the water from a dry barrel of a recoilless underwater firearm with 12th gauge ammunition (12/70), the cavitating core “prototype” with the mass of 70 g and with an aluminum discarding sabot with the mass of 4 g has a muzzle velocity of 600 m/s, as specified in patents RU 2 651 318 C2 of 19 Apr. 2018 and U.S. Pat. No. 10,591,232 B2 of 17 Mar. 2020 and EP 3 431 915 B1 of 20 Oct. 2021. The cavitating core (G.sub.3) of the given invention has a mass of 75 g due to a more accurate approximation of its enveloping contour (R) to the contour cavity (W) formed in the water, therefore, its muzzle velocity, considering the mass of the plastic discarding sabot (3 g), will be V.sub.0=585 m/s at a similar shot. And its velocity (V) and energy (E) at the underwater distance (S) will have the following parameters:

S=5 m: V.sub.5=496 m/s and E.sub.5=9220 Joules;
S=10m: V.sub.10=421 m/s and E.sub.10=6650 Joules;
S=15 m: V.sub.15=357 m/s and E.sub.15=4780 Joules.

[0086] These parameters of the cavitating core (G.sub.3), considering its loss of cavitation stability in soft tissues, can ensure the defeat of a large hunting object. For comparison, the well-known “Brenneke” bullet with the diameter of 18.5 mm and the mass of 31.5 g, which is used in 12th gauge shotgun ammunition (12/70 Magnum) for hunting large animals, has a muzzle velocity and energy V.sub.0=460 m/s and E.sub.0=3335 Joules, and at a distance of 50 m in the air has a velocity and energy V.sub.50=352 m/s and E.sub.50=1951 Joules, as indicated on the website: www.brenneke-ammunition.de/en/shotgun-ammunitioniclassic/

[0087] An increase in the energy characteristics of a cavitating core at the air and underwater trajectory is achieved by increasing its mass when high-density materials based on tungsten or lead are used in its construction.

[0088] Moreover, in ammunition designs, where the cavitating core with a tail fin stabilizer 32 is fixed with a sabot, and not with a disk 34, it is possible to reduce the outer diameter of the disk 34 to the outer diameter of the bushing 31. This will significantly reduce the aerodynamic drag of the aft part 5 by eliminating the vortex (base) drag of the disk 34, which is designed to quickly reduce the angles of attack of the cavitating core when firing from the air into the water from a short air distance. In this design, the bushing 31 and the tail fin stabilizer 32 may be made of an aluminum alloy with the density ρ=2.7 g/cm.sup.3, which will provide an additional displacement of the center of mass of the cavitating core (G.sub.3) to the head portion 1 and ensure its stability in the air and in the water without a disk 34.

[0089] FIG. 6 shows a schematic view of a fragment of 12th gauge shotgun ammunition (12/70) with a fastened cavitating core (G.sub.4). The ammunition includes: a brass cartridge case 40 with a primer and propellant charge 41, in the neck of which a cavitating core (G.sub.4) with a discarding sabot 42 is fastened. Dimensions of the outer surfaces of the head portion 1 and the central portion 4 of the cavitating core (G.sub.4), as well as its length and caliber (D) at the length (L) are equal to those of the cavitating core (G.sub.3). In this case, the aft portion 5 of the cavitating core (G.sub.4) is made in the form of a combination of two truncated cones (E) and (F), where the larger base of the cone (F) is conjugated with the gliding surface 6, the contour of which corresponds to the gliding surface 6 with a cylindrical tail section (disc 34) of the cavitating core (G.sub.3). At the same time, the diameter of the conjugation (D.sub.X34) of the two truncated cones (E) and (F) at the length (L.sub.X3) is 5% less than the diameter (D.sub.X3) at the length (L.sub.X3) of the cavitating core (G.sub.3). The reduced mating diameter (D.sub.X34) excludes flushing and gliding of the outer surface of the truncated cone (F) during the movement in the cavity formed in the water, because the center of mass of the cavitating core (G.sub.3) should be located at the length X≥0.3 D in front of the leading edge of the gliding surface 6 located at the length (L) according to the terms of this invention.

[0090] The mass of the cavitating core (G.sub.4) is 120 g when its jacket 43 is made of an easily deformable non-ferrous alloy, namely, of brass with the density ρ=8.4 g/cm.sup.3 and filled with lead 44 with the density ρ=11.3 g/cm.sup.3. The base pocket 45 allows placing a part of the propellant charge 41 in it and shifts the center of mass of the cavitating core to the head at the length X=0.97 D from the leading edge of the gliding surface 6 located at the length (L), which provides rectilinear cavitation movement in the water.

[0091] The discarding sabot 42 has the mass of 3 g when made of the PA-6 type plastic with the tensile strength Rm=65 . . . 70 MPa and the density ρ=1.12 . . . 1.15 g/cm.sup.3, and the diameter of its outer surface (D.sub.3) is equal to the caliber (D) of the cavitating core. The symmetry of the outer surface of the sabot 42 with the diameter (D.sub.3) and the gliding surface 6 with the diameter (0) is ensured by fastening the sabot 42 on the thread 37 with fixation on the conical surface 46.

[0092] The cavitating core (G.sub.4) is fastened into the cartridge case 40 by its gliding surface 6. Similarly, the cavitating core (G.sub.3) is fastened into the cartridge case 40 by its gliding surface 6 of the disc 34. At the length of the cavitating cores (G.sub.3) and (G.sub.4) equal to 4.8 D, the length of the ammunition is 150 mm and exceeds the standard length of the 12th gauge shotgun ammunition (12/70 and 12/76), but this is permissible at manual loading of a recoilless underwater firearm. During a shot, the obturation of the propellant gas in the barrel is provided by the gliding surface 6 and the sabot 42.

[0093] At a shot in the air from a smooth barrel, the cavitating core (G.sub.4) is stabilized by the aerodynamic resistance of the aft portion 5 and the plastic sabot 42 that cannot separate along three narrow longitudinal slots 47 without a centrifugal rotation force. But, when the plastic sabot 42 enters the water it separates along three narrow longitudinal slots 47 due to the hydraulic resistance of the water and discards from the cavitating core. Of course, the plastic sabot 42 significantly increases the aerodynamic drag, but this is acceptable when shooting from the air into the water at a short distance. At a shot in the air from a rifled barrel, the cavitating core (G.sub.4) is stabilized by spin after the sabot 42 separates along three narrow longitudinal slots 47 due to the centrifugal rotation forces and discards from the cavitating core.

[0094] Cavitation movement in the cavity formed in the water and loss oaf cavitation stability in a heterogeneous and compressible aqueous-containing medium of the cavitating core (G.sub.4) is similar to the cavitating core (G.sub.3), since they have an identical enveloping contour line (R) and the dimensions of outer surfaces, except for the diameter (D.sub.X34) at the length (L.sub.X3).

[0095] The cavitating core (G.sub.4) has a bigger mass and lower muzzle velocity, but more energy on the underwater trajectory, than the cavitating core (G.sub.3). At a shot in the air or in the water from a dry barrel of the recoilless underwater firearm, the cavitating core (G.sub.4) with the mass of 120 g with the discarding sabot with the mass of 3 g will have a muzzle velocity V.sub.0=465 m/s, considering the speed of the free rollback of the barrel, and its velocity (V) and energy (E) at underwater distance (S) will have the following parameters:

S=5 m: V.sub.5=420 m/s and E.sub.5=10580 Joules;
S=10m: V.sub.10=380 m/s and E.sub.10=8660 Joules;
S=15 m: V.sub.15=345 m/s and E.sub.15=7140 Joules.

[0096] This example shows that the cavitating core (G.sub.4) with a bigger mass has by 30-50% bigger energy parameters at the underwater trajectory than the cavitating core (G.sub.3).

[0097] Comparison of the enveloping contour (R) of the cavitating c ore (G.sub.3 or G.sub.4) of the given invention and it “analog” shows that the enveloping contour (R) of the “analog” is limited by the diameter 0.4 D=7.4 mm at the length of 0.4 D. But in the cavitating core (G.sub.3) or (G.sub.4), the enveloping contour (R) is limited by the diameter D.sub.X=7.68 mm at the length L.sub.X=0.40. This shows that the enveloping contour (R) of the given invention is closer to the cavity contour (W) than the enveloping contour (R) of the “analog”.

[0098] Comparative calculation of the enveloping contour line (R) of the cavitating core (G.sub.3 or G.sub.4) using the “prototype” equation:

D.sub.X=d×[1+(L.sub.X/d)×(2sin φ/π).sup.1/N].sup.N

shows that at sizes: d=3.15 mm, φ=120° and N=0.478 between the cavity contour (W) and caliber D=18.5 mm of the cavitating core “prototype”, the design gap δ.sub.L=2.30 mm and the maximal inclination angle ω=0.8° at the length L=80 mm are formed. And the minimum design gaps are δ.sub.1=0.84 mm, δ.sub.2=0.72 mm and δ.sub.3=0.24 mm that can be formed between the enveloping contour (R) and the cavity contour (W) at the lengths L.sub.X1=6 mm, x.sub.X2=16 mm and L.sub.X3=60 mm, respectively.

[0099] This calculation shows that in the cavitating core “prototype” the gaps (δ.sub.1), (δ.sub.2) and (δ.sub.3) are 2.3, 4.8 and 6 times bigger than the gaps (δ.sub.1), (δ.sub.2) and (δ.sub.3) in the given invention. This provides a stable cavitation movement of the cavitating core “prototype” in the cavity formed in the water and in a heterogeneous and compressible aqueous-containing medium, which was confirmed by comparative shooting into ballistic gelatin blocks with cavitating cores “prototype” and cavitating cores of the given invention.

[0100] Analysis of the enveloping contour line (R) of the cavitating core (G.sub.3 or G.sub.4) using a cavity equation from the well-known “RAMICS” presentation shown on the website:

www.scribd.com/document/342233681/30x173-for-RAMICS
where the cavity equation looks like:

y=d/√{square root over ((kx/d )+1,)}wherein:

y=R=½D—is the current radius of the cross-sections of the formed cavity at the current length (x), (in mm or inch);
d—is the diameter of the cavitating edge, (in mm);
k=2 c.sub.X=2 sin φ/π—is doubled cavitation drag index (c.sub.X) for the nasal surface that made in the form of a flat face (φ=180°);
x—is the current length (L.sub.X) of the formed cavity from the cavitating edge, (in mm), shows that when the surface 6 is glided along the cavity contour (W), the design gap
δ.sub.L=1.10 mm and the maximum inclination angle ω=0.4° at the length L=80 mm are formed. At the same time, the negative minimum design gaps (δ.sub.1=−61 mm, δ.sub.2=−0.60 mm and δ.sub.3=−0.18 mm) will be formed between the enveloping contour (R) and the cavity contour (W) at the lengths L.sub.X1=6 mm, L.sub.X2=16 mm and L.sub.X3=60 mm, respectively.

[0101] This analysis shows that the calculated cavity equation in the “RAMICS” presentation is underestimated relative to the actual cavity contour (W), which in principle does not allow creating the enveloping contour line (R) of the cavitating core of the given invention using the cavity equation from the “RAMICS” presentation.

[0102] The presented examples show that the given invention improves the efficiency of the cavitating core by approaching the contour of its outer surface to the cavity contour (W) formed in the water, increasing its mass and improving its stopping power due to the loss of its cavitation stability and overturn in inhomogeneous (heterogeneous) and a compressible aqueous-containing medium with increasing the area of contact with the target.