MULTI-PIECE PROJECTILE

TECHNICAL FIELD

The present disclosure relates generally to firearms ammunition and more particularly to a multi-piece projectile.

BACKGROUND

A firearms cartridge commonly includes four main components, namely, a cartridge casing, a primer, a propellant charge, and a projectile. The cartridge casing traditionally has been made of brass and has a cylindrical body between a head and a mouth. The casing may reduce in diameter (or “neck down”) to a smaller diameter region that retains the projectile. The head of the casing often defines a recessed rim that is used to extract the cartridge casing from the firearm's chamber. The head of the casing houses a primer, which is centrally located in center-fire cartridges. The primer includes a reactive material that ignites the propellant when the firing pin or hammer strikes the primer. The propellant, typically a powder, is contained in the body of the casing and burns to generate pressure in the firearm chamber to fire the projectile. The projectile is retained in the mouth of the casing and often has a cylindrical body and tapers along an ogival portion to a tip that is often flat or rounded. The projectile can be one of several forms, including fully jacketed, soft point, hollow point, jacketed soft point, and other configurations.

SUMMARY

The present disclosure is directed to a multi-piece projectile for small arms, such as a rifle. In one embodiment, the projectile includes a penetrator and a jacket. The penetrator may be fully encased by the jacket or may include an ogival portion that extends out of the distal end of the jacket. In some embodiments, the projectile also includes a slug within the jacketed portion and located proximally of the penetrator. A proximal end portion or base of the penetrator abuts a corresponding surface on the jacket, or the slug contained within the jacket when present, defining an interface between these components. This interface is configured to maintain the axial alignment of the penetrator, jacket, and slug (when present). In one example embodiment, the base of the penetrator has a frustoconical shape that is received in a corresponding frustoconical recess defined in a distal face on the inside of the jacket. In another example, a slug is retained inside the jacket and the base of the penetrator is received in a corresponding recess defined in a distal face of the slug.

The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been selected principally for readability and instructional purposes and not to limit the scope of the disclosed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a projectile having multiple components, in accordance with an embodiment of the present disclosure.

FIG. 2 is a side view of the projectile of FIG. 1.

FIG. 3 is a side view showing a longitudinal section of a two-piece projectile, in accordance with an embodiment of the present disclosure.

FIG. 4 is a front perspective view of the section shown in FIG. 3.

FIG. 5 is a side view showing a longitudinal section of a three-piece projectile, in accordance with an embodiment of the present disclosure.

FIG. 6 is a front perspective view of the section shown in FIG. 5.

FIGS. 7-10 illustrate side views of a longitudinal section of penetrators, in accordance with some embodiments of the present disclosure.

FIG. 11 shows target data collected using prior art projectiles.

FIGS. 12 and 13 show target data collected using a two-piece projectile, in accordance with the present disclosure.

FIG. 14 shows target data collected using a three-piece projectile, in accordance with the present disclosure.

FIG. 15 illustrates steps in a method of manufacturing a three-piece projectile, in accordance with an embodiment of the present disclosure.

FIG. 16A illustrates a cross-sectional view of a jacket pre-form, in accordance with an embodiment of the present disclosure.

FIG. 16B illustrates an elevational view of the jacket pre-form of FIG. 16A.

FIG. 17 illustrates a cross-sectional view of a slug, in accordance with an embodiment of the present disclosure.

FIG. 18 illustrates a cross-sectional view of a jacket pre-form in accordance with an embodiment of the present disclosure.

The figures depict various embodiments of the present disclosure for purposes of illustration only. Numerous variations, configurations, and other embodiments will be apparent from the following detailed discussion.

DETAILED DESCRIPTION

Disclosed is a multi-piece projectile for a firearm, in accordance with the present disclosure. In one aspect, a two-piece firearm projectile includes a jacket and a penetrator. The proximal end of the penetrator is received in and mates with a corresponding recess defined in the distal inside surface of the jacket. A three-piece projectile includes a jacket, a slug, and a penetrator. The slug and at least part of the penetrator are encased by the jacket, where the slug is positioned between the base of the jacket and the proximal end or base of the penetrator. The proximal end of the penetrator overlaps axially with the distal end of the slug. In one example, a frustoconical base of the penetrator is received in and mates with a frustoconical recess defined in the distal end of the slug.

In example embodiments, the jacket and slug can be made of copper or a copper alloy and the penetrator can be made of steel. The axial overlap of the proximal end of the penetrator with either the recess of the jacket or with the recess of the slug results in a self-aligning assembly that distributes setback forces more evenly than in existing projectiles. The resulting projectile reduces or eliminates undesirable random deformations that may occur in projectiles lacking the axial overlap. Accordingly, projectiles according to the present disclosure exhibit a reduction in random deformations in the barrel and therefore have improved precision over existing projectiles.

Overview

Upon firing, a projectile must form a seal with the gun's bore. Without a strong seal, gas from the propellant charge leaks past the bullet, reducing efficiency and accuracy. As part of forming a seal with the gun's bore, the bullet engages the rifling grooves and lands in the barrel, where the bullet has a slightly larger diameter than the barrel and yields to the rifling. To achieve this deformation, the bullet has a relatively soft outer surface that forms a seal as the bullet is forced through the rifled bore by pressure of the burning propellant. A soft material such as lead or copper is used for some projectiles, including those with a lead core and jacket of copper or other gilding material. In such configuration, the mass of the lead core delivers kinetic energy to the target while the harder jacket material protects the softer core as the bullet passes through the barrel and during flight to the target.

Firearms have recently been designed to operate with higher chamber pressures, therefore resulting in greater muzzle velocity for the projectile and other desired ballistics. For example, rifles utilize a peak chamber pressure of about 80,000 psi, a significant increase over the peak chamber pressure of 65,000 psi used previously as a standard for rifle ammunition. With this increased chamber pressure, the bullet experiences an even greater setback force upon firing the rifle. In the case of existing projectiles that have a slug and a penetrator, setback forces can cause the flat distal face of the slug to expand radially outward that results in a bulge on the exterior of the jacket. This bulge causes copper fouling in the barrel as well as in-bore balloting. Additionally, the penetrator can become misaligned with the central axis of the projectile, resulting in balloting and irregular flight due to unbalanced mass and random deformation. Accordingly, a need exists for a projectile with improved precision.

The present disclosure addresses this need and others by providing a multi-piece projectile that reduces irregular deformation as it passes through the barrel, and in turn exhibits more consistent flight. As a result, precision is improved.

In accordance with some embodiments of the present disclosure a two-piece projectile has a penetrator portion and a jacket portion. The base of the penetrator portion has an interlocking interface with the inside surface of the jacket. For example, the base of the penetrator has a frustoconical shape that is received in a corresponding frustoconical recess in the jacket portion. Similarly, a three-piece projectile includes a slug in the base of the jacket behind the penetrator, where the interface between the penetrator and slug has a frustoconical shape. Upon firing, this interface distributes setback forces over a greater area and reduces or eliminates bulge formation. The mating interface also maintains the axial alignment of the penetrator (and slug, when present) along the central axis of the projectile. For example, the rigidity of the penetrator and slug functions as a splint to prevent lateral movement of the penetrator. As a result, the penetrator remains axially aligned. Experiments have shown a reduction in group size of 60% or more at 100 yards. For example, projectiles in accordance with the present disclosure provide a group size of about two inches or less while existing technology has a group size of between five and a half inches or more.

A projectile as disclosed herein can be configured with a variety of diameters and weights. One example projectile has a 6.5 mm diameter and 127 grain weight with a steel penetrator, copper slug, and copper jacket. Another example projectile has a 5.56 mm diameter and 55 grain weight. Another example projectile has a 7.62 mm diameter and weight from 120 to 180 grains. Note that projectiles configured for 6.5mm, 5.56 mm, and 7.62 cartridges may have actual diameters of about 6.7 mm, 5.7 mm and 7.8 mm, respectively. Other calibers and bullet weights can be used as will be appreciated.

Note that while generally referred to herein as a penetrator for consistency and ease of understanding the present disclosure, the disclosed projectiles are not limited to that specific terminology and the penetrator alternately can be referred to as a core or other terms. Also, while generally referred to herein as a projectile, the disclosed projectile can alternately be referred to as a bullet. As will be further appreciated, the particular configuration (e.g., materials, dimensions, etc.) of a projectile as disclosed herein may be varied, for example, depending on whether the intended use is for military, competitive shooting, hunting, or other application. Numerous variations and embodiments will be apparent in light of this disclosure.

Example Embodiments

FIGS. 1 and 2 illustrate a front perspective view and a side view, respectively, of a projectile 100, in accordance with an embodiment of the present disclosure. In this example, the projectile 100 has an elongated shape configured for use in a rifle cartridge. The projectile 100 extends along a central axis 101 from a proximal end 102 to a distal end 104 or tip. The projectile 100 includes a jacket 120 and a penetrator 150. In one embodiment, the jacket 120 is made of copper or copper alloy, although other gilding metals can be used. In one embodiment, the penetrator 150 is made of steel. Other acceptable materials include copper, tungsten, and titanium. In some embodiments, the projectile 100 includes a slug 180 (shown, e.g., in FIG. 5) on the inside of the jacket 120, axially between the penetrator 150 and the proximal end 102 of the jacket 120.

The base or proximal end portion 102a of the projectile 100 has a slight taper to the proximal end 102, known generally as a boat tail configuration. Located distally of the boat tail end portion 102a is a substantially cylindrical body portion 106, which transitions to an ogival portion 108. The surface of the body portion 106 may referred to as a bearing surface 106a. In some embodiments, the ogival portion 108 has a hybrid ogive shape with a shorter tangent ogival portion 108a and a longer secant ogive portion 108b. In some embodiments, the ogival portion 108 includes a distal portion of the penetrator 150 that extends forward of the jacket 120. In other embodiments, the penetrator 150 is entirely encased by the jacket 120. In yet other embodiments, the projectile 100 has a linear taper between the body portion 106 and the distal end 104. For example, the linear taper can extend along all or part of the length between the body portion 106 and distal end 104. Optionally, an outer surface of the body potion 106 can define a plurality of circumferential grooves 129 or protrusions (shown in FIGS. 16 and 18).

FIGS. 3 and 4 illustrate a side view and a front perspective view, respectively, of a longitudinal section of a projectile 100, where the section is taken through the central axis 102, in accordance with an embodiment of the present disclosure. In this example, the projectile 100 is a two-piece projectile that includes a jacket 120 and a penetrator 150. The jacket 120 includes a solid proximal portion 122 and defines a cavity 124 distally thereof that envelops at least part of the penetrator 150. The solid proximal portion 122 can extend axially from the proximal end 102 to a point between the proximal end 102 and the cylindrical body portion 106, can extend axially into the body portion 106, or simply can extend axially into the tapered proximal end portion 102a. In this example, the solid proximal portion 122 extends into the body portion 106.

A distal face of the solid proximal portion 122 of the jacket 120 defines a recess 126 that mates with the proximal end portion 152 of the penetrator 150. As shown here, the recess 126 has a frustoconical shape that reduces in inner diameter moving proximally from the body portion 106 towards proximal end 102. The recess 126 provides regions of increased wall thickness laterally adjacent the proximal end portion 152 of the penetrator 150. The increased wall thickness stabilizes the proximal end portion 152 and reduces deformation better than the relatively thin wall thickness along the body portion 106, for example.

In one embodiment, the wall thickness at the end of the proximal end of the penetrator 150 is about 0.10″, while the wall thickness is about 0.03″ along the body portion 106 and ogival portion 108. In other embodiments, the recess 126 can be shaped as a socket or some other geometry of reduced inner diameter compared to the body portion 106, where the socket receives the similarly shaped proximal end portion 152 of the penetrator 150. For example, the cavity defines a socket of cylindrical, conical, or frustoconical shape to receive a corresponding protrusion or other geometry at the proximal end portion 152 of the penetrator 150. In one embodiment, sides of the proximal end portion 152 are oriented at an angle a about 30° with respect to the central axis 101.

The penetrator 150 has a proximal end portion 152 of frustoconical or conical shape that reduces in diameter moving proximally. The proximal end portion 152 mates with the recess 126 defined in the jacket 120. Since the proximal end portion 152 and recess 126 are rotationally symmetrical, the penetrator 150 self-centers axially. Thus, as a result of the axial overlap between the recess 126 and the penetrator, and the increased wall thickness of the jacket 120 along the proximal end portion 152, the penetrator 150 resists lateral movement and instead maintains axial alignment as the projectile 100 enters and passes through the barrel.

Referring now to FIGS. 5 and 6, a side view and a front perspective view, respectively, illustrate a longitudinal section of a projectile 100 taken through the central axis 101, in accordance with an embodiment of the present disclosure. In this example, the projectile 100 is a three-piece projectile that includes a jacket 120, a penetrator 150, and a slug 180. The jacket 120 includes a solid proximal portion 122 and defines a cavity 124 distally thereof that envelops the slug 180 and at least part of the penetrator 150. In this example, the solid proximal portion 122 has an axial thickness of about 0.05″ to 0.10″. The slug 180 is positioned axially between the solid proximal portion 122 and the penetrator 150.

The distal end of the slug 180 defines a recess 186 that mates with and axially overlaps the proximal end portion 152 of the penetrator 150. Similar to recess 126 discussed above with reference to FIGS. 3-4, the recess 186 defined by the slug 180 can have a frustoconical shape that reduces in diameter moving proximally. The result is that laterally outer portions 182 of the slug 180 overlap axially with the proximal portion 152 of the penetrator 150. In addition to the slug 180 overlapping with the penetrator 150, the laterally outer portions 182 may function to reinforce the jacket 120 along the body portion 106 where the penetrator 150 contacts the slug 180. Together, the slug 180 and penetrator 150 function as a splint that maintains the axial alignment of the penetrator 150 along the projectile's central axis 101 due at least in part to the stiffness of the penetrator 150, which can be made of steel. In other embodiments, the cavity 186 can be shaped as a socket or have some other geometry configured to receive and mate with the proximal end portion 152 of the penetrator 150. For example, the recess 186 at least in part defines a cylindrical, conical, or frustoconical shape to receive a corresponding protrusion at the proximal end portion 152 of the penetrator 150.

In this example shown in FIGS. 5-6, the jacket 100 has a side wall thickness from about 0.02″ to about 0.04″ along the slug 180 and part of the penetrator 150. The axial wall thickness at the proximal end 102 of the jacket 120 can be 0.03″ or more, including 0.05″ or greater, 0.07″ or greater, and 0.10″ or greater. The jacket 100 terminates adjacent a tip portion 156 of the penetrator 150, where the penetrator 150 defines a radially outward shoulder 158. The end of the jacket 120 abuts the shoulder 158 so that the outside surfaces of the jacket 120 and penetrator 150 are substantially continuous along the ogival portion 136.

Referring now to FIGS. 7-10, side views illustrate cross sections of a penetrator 100 in accordance with some embodiments of the present disclosure. In each of FIGS. 7-10, the proximal end portion 152 of the penetrator 150 has a non-planar profile and is configured to be received in a corresponding recess 126, 186 of the jacket 120 or slug 180. The penetrator 150 also includes a body portion 154 of substantially cylindrical geometry, an ogival portion 155, and a tip portion 156. As noted above, a shoulder 158 extends radially outward between the ogival portion 155 and the tip portion 156.

In the example of FIG. 7, the proximal end portion 152 has a frustoconical shape, such as discussed above. In the example of FIG. 8, the proximal end portion 152 is configured as a cylindrical protrusion of reduced diameter compared to the body portion 154. In the example of FIG. 9, the proximal end portion 152 is configured as a frustoconical protrusion, where the entire protrusion has a reduced diameter compared to the body portion 154. In the example of FIG. 10, the proximal end portion 152 has a conical taper to a point.

FIGS. 11-14 represent experimental data collected from target faces with bullet hits for 10 shots fired at 101 yards from a test barrel. In each of these figures, the grey-filled circle represents a 5″ target circle. Smaller black circles represent bullet strikes. The unfilled black circle has a radius equal to the mean radius of the group and the dashed line represents the extreme spread or group size. The plus symbol in each figure represents the center of the group. The data shown in these targets was acquired in the same environmental conditions, test barrel, and firing procedure.

The target of FIG. 11 shows a group using existing bullets having a penetrator and jacket, where the base of the penetrator is flat and perpendicular to the central axis of the projectile. The group shown in FIG. 11 from existing bullets has a mean radius of 2.1 inches and a group size of 5.6 inches. The projectile used to obtain this group is an example of the existing projectiles and precision that is improved upon by projectiles of the present disclosure.

The targets of FIGS. 12 and 13 represent bullet strikes using two-piece bullets as shown, for example, in FIGS. 3-4. In FIG. 12, the group has a mean radius of 0.6 inch and a group size of 1.9 inches. The mean radius here is 28.6% of that achieved using existing bullets, and the group size is 33.9% of that achieved using existing bullets discussed for FIG. 11. In FIG. 13, the group has a mean radius of 0.5 inch and a group size of 1.8 inches. For FIG. 14, the mean radius is 23.8% of that shown in FIG. 11 and the group size is 32.1% of that shown in FIG. 11.

The target of FIG. 14 represents bullet strikes using three-piece bullets such as shown, for example, in FIGS. 5-6. The mean radius of the group is 0.5 inch, and the group size is 1.8 inches. The mean radius of the group is 23.8% of that achieved using existing bullets and group size is 32.1% of that achieved using existing bullets discussed for FIG. 11.

FIG. 15 illustrates a method 300 of making a projectile having a non-planar interface between the penetrator and the slug. In step 310, method begins with providing a jacket pre-form, a slug, and a penetrator. Each of these components can be formed by turning on a Swiss machine. The jacket pre-form can have a cup-like geometry with an open top end and boat-tail bottom end. The slug is sized and shaped to snugly fit into the base of the jacket pre-form. In one embodiment, the jacket pre-form and slug are made of copper or a copper alloy and the penetrator is made of steel. Other materials can be used as deemed suitable for a specific application. When the projectile is a two-piece projectile, the slug is omitted.

FIGS. 16A and 16B show a side cross-sectional view and a side view of a grooved jacket pre-form 120′ for a two-piece projectile, in accordance with one embodiment. In this example, the jacket pre-form 120′ defines recess 126 having a frustoconical shape. Grooves 129 have been machined or formed in the outside surface and are spaced axially by about 0.10″. FIG. 17 illustrates a side, cross-sectional view of a slug 180 defining a frustoconical recess 186, In accordance with an embodiment. FIG. 18 illustrates a side, cross-sectional view of a jacket pre-form 120′ configured for a three-piece projectile, in accordance with an embodiment. In this example, the jacket pre-form 120′ is configured to receive the slug 180 shown in FIG. 17. The jacket pre-form 120′ includes optional grooves 129 in the outside surface.

In some embodiments, providing the slug and penetrator includes forming a recess in the distal end of the slug and forming a correspondingly shaped proximal end portion on the penetrator. Examples of the slug and penetrator are discussed above.

In step 320, the slug is placed through the open end of the jacket pre-form into the bottom of the jacket pre-form. If the projectile is a two-piece projectile, step 320 can be omitted.

In step 330, the penetrator is installed into the jacket pre-form with the proximal end portion received in the recess defined in the distal end of the slug. If the projectile is a two-piece projectile, the penetrator is installed into a jacket pre-form with the proximal end portion received in the recess defined in the bottom of the jacket pre-form.

In step 340, the jacket pre-form is swaged to tightly engage the outside surface of the slug and penetrator. In some embodiments, the pre-form is closed on and abuts the shoulder on the tip portion 156 of the penetrator.

In step 350, optional machining may be performed, which can include fine tuning the outer diameter of the assembled projectile, forming circumferential grooves in the body portion of the jacket, and/or removing excess jacket material adjacent the shoulder of the penetrator. The projectile can be polished as needed.

Further Example Embodiments

The following examples pertain to further embodiments, from which numerous permutations and configurations will be apparent.

Example 1 is a firearm projectile comprising a jacket extending along a central axis, where an inside surface of the jacket defines a recess aligned with the central axis. A penetrator extends along the central axis and is at least partially retained in the jacket. The penetrator has a proximal end portion received in the recess and has a shape corresponding to a shape of the recess. An interface between the proximal end portion of the penetrator and the recess is non-planar such that the recess axially overlaps the proximal end portion of the penetrator.

Example 2 includes the projectile of Example 1, where the recess and the proximal end portion each includes a conical taper.

Example 3 includes the projectile of Example 2, where the proximal end portion defines a frustocone.

Example 4 includes the projectile of Example 3, where a base of the frustocone is smaller than a body of the penetrator immediately adjacent the base.

Example 5 includes the projectile of Example 1, where the penetrator has a body portion of a first diameter along the inside surface of the jacket and where the proximal end portion defines a protrusion extending axially from the body and having a second diameter less than the first diameter.

Example 6 includes the projectile of Example 5, where the second diameter reduces moving in a proximal direction.

Example 7 includes the projectile of Example 5, where the protrusion is cylindrical.

Example 8 includes the projectile of any one of Examples 1-7, where the jacket completely encases the penetrator.

Example 9 includes the projectile of any one of Examples 1-8, where the jacket comprises copper.

Example 10 includes the projectile of Example 9, where the jacket consists essentially of copper.

Example 11 includes the projectile of any one of Examples 1-10, where the penetrator comprises in majority part one of steel, tungsten, and titanium.

Example 12 is firearm projectile comprising a jacket extending along a central axis, the jacket having a closed base and defining a cavity. A slug in the cavity contacts an inside distal surface of the closed base of the jacket, where a distal end of the slug defines a recess aligned with the central axis. A penetrator extends along the central axis and is at least partially retained in the jacket. The penetrator has a proximal end portion received in the recess and having a shape corresponding to the recess, where an interface between the proximal end portion of the penetrator and the recess is non-planar such that the recess axially overlaps the proximal end portion of the penetrator.

Example 13 includes the projectile of Example 12, where the recess and the proximal end portion each includes a conical taper.

Example 14 includes the projectile of Example 13, where the proximal end portion defines a frustocone.

Example 15 includes the projectile of Example 14, where a base of the frustocone is smaller than a body of the penetrator immediately adjacent the base.

Example 16 includes the projectile of Example 12, where the penetrator has a body portion of a first diameter along the inside surface of the jacket and where the proximal end portion defines a protrusion extending axially from the body and having a second diameter less than the first diameter.

Example 17 includes the projectile of Example 16, where the second diameter reduces moving proximally along the protrusion.

Example 18 includes the projectile of Example 16, where the protrusion is cylindrical.

Example 19 includes the projectile of any one of Examples 12-18, where the jacket completely encases the penetrator.

Example 20 includes the projectile of any one of Examples 12-19, where the jacket comprises copper, and where the penetrator comprises in majority part steel, tungsten, or titanium.

Example 21 includes the projectile of any one of Examples 12-20, where the slug comprises lead.

Example 22 includes the projectile of any one of Examples 1-21, where an outside of the jacket defines one or more circumferential grooves.

Example 23 is a rifle cartridge comprising the projectile of any one of Examples 1-22.

Example 24 includes the cartridge of Example 23, where the projectile has a bearing surface with a diameter of about 7.8 mm.

Example 25 includes the cartridge of Example 23, where the projectile has a bearing surface with a diameter of about 5.7 mm.

Example 26 includes the cartridge of Example 23, where the projectile has a bearing surface with a diameter of about 6.7 mm.

The foregoing description of example embodiments has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the present disclosure be limited not by this detailed description, but rather by the claims appended hereto. Future-filed applications claiming priority to this application may claim the disclosed subject matter in a different manner and generally may include any set of one or more limitations as variously disclosed or otherwise demonstrated herein.

MULTI-PIECE PROJECTILE

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