US3311962A - Method of making an expanding point bullet - Google Patents

Description

April 4, 1967 BURNS, JR 3,311,962

METHOD OF MAKING AN EXPANDING POINT BULLET (lrlginal Filed April 1, 1965 2 Sheets-Sheet 1 Fig :2,

INVENTORZ 4 ART/g1? H BMW/5 w?- A 1U 71% 5 Q April 4, 1967 A. H. BURNS, JR

METHOD OF MAKING AN EXPANDING POINT BULLET 2 Sheets-Sheet 2 Orlginal Filed April 1, 1965 IN VENTOR.

Arema/Q H (/AMS, JR.

BY w v United States Patent ()fiice 3,3 l 1,962 Patented Apr. 4, 1967 3,311,962 METHOD OF MAKING AN EXPANDING POINT BULLET Arthur H. Burns, Jr., Cheshire, Conn., assignor to Olin Mathieson Chemical Corporation, a corporation of Y rginia Original application Apr. 1, 1963, Ser. No. 269,280, now Patent No. 3,157,137, dated Nov. 17, 1964. Divided and this application June 30, 1964, Ser. No. 387,259 4 Claims. (Cl. 29-113) This application is a division of my copending application Ser. No. 269,280 filed Apr. 1, 1963, which is now U.S. Patent No. 3,157,137, granted Nov. 17, 1964.

This invention relates to projectiles and more specifically to an improvement in projectiles of the expanding type known as mushrooming bullets, and to the method of their fabrication.

Bullets having an expanding point generally consist of a core of soft malleable material such as lead or a lead alloy and a relatively hard jacket, usually a copper base alloy, capable of resisting stripping from the core while taking not only the rifling action of the gun but also the mushrooming action of penetration of the target.

Jacketed bullets of this type include various bullet designs such as the soft-point bullets having a rounded nose of core material, and the more sharply pointed bullets having higher ballistic performance at the longest range. One such sharply pointed bullet is the hollow point bullet having a portion of the core exposed but recessed within the jacket at the nose. Another has a jacket extending over the ogivally pointed nose with modifications in the jacket to enable deformation at the nose.

Heretofore, various modifications have been made in this general jacketed bullet construction in order to improve the expansion characteristics of this type of bullet. According to one modification, metal is removed from the interior of the base jacket to provide it with longitudinally extending cuts or slits partially through it at the mouth. This arrangement has been tried with or without a tip jacket. The cuts have been extended all the way through to indent the edge and provide spaced petals or serrations :at the mouth of the base jacket. Such projectiles have also been constructed with a recess of one type or another in the lead core at the point. According to the other and more complicated modifications, holes have been pierced from one side of the point to the other,

separate anvil pieces have been embedded in the point, and

corrugations have been tried in the tip jacket.

How the objects and advantages of this invention are obtained will become apparent from a general discussion together with a description of specific embodiments shown in the drawing in which:

FIG. 1 is a front view of one embodiment of the projectile according to this invention, shown enlarged;

FIG. 2 is an elevational cross sectional view of the embodiment of FIG. 1 taken on line II-H, and shown partly in section, with the same enlargement;

FIG. 3 is another front view of a still further preferred embodiment, similarly enlarged, of only the tip;

FIG. 4 is an elevational side view in longitudinal cross section showing a die apparatus with a preliminary assembly positioned therein for an intermediate manufacturing operation for making a bullet of this invention;

FIG. 5 is an end view taken on line VV looking down upon the assembly of FIG. 4 after completion of the operation shown; and

FIG. 6 is an elevational side view showing a point shaping die in cross section and the substantially completed bullet positioned in the die and formed therein completed adjacent the nose.

In accordance with this invention, there is provided an expanding bullet similar to the hollow point type having a pore enfolded within a base jacket and having a base acket constructed with special creasing andswaging at the mouth so as to achieve at least a proclivity to uniform and full inward ribbing sometimes accompanied by partial splitting along predetermined lines while at the same time offering yielding but firm support to the expanding core with a scoop-like unfolding structure to avoid excessive core fragmentation and separation. This is done without cutting away and removing any part of the much needed jacket support to give a significant improvement in uniformity of mushrooming, particularly at maximum ranges, i.e. at the lowest velocities. In an uncomplicated and economical way, the uniform expansion. characteristics of this type of bullet are further extended so that the bullet behavior even at very low velocities has a remarkable uniformity which is comparable with that obtained at other ranges and velocities including the closest range and highest velocity.

The malleable core may be made either from a solid slug or from metal powder, which is compressed to control density and rate of bullet upset.

The improvement is obtained by pinch-pleating the tapering mouth of the base jacket by means of preliminary creasing in such a way as to form thickened staves and a number of deeply inwardly extending folded webs, each between adjoining staves to form stave-like flanged panels at the edge of the jacket. Each folded web involves one very sharp bend, a single bend, at: which the metal is overstressed to have at least a pronounced proclivity to split, and also involves an internal thickness of web extending radially into abutment with adjoining ribs. Abutment is back of the tip.

The resultant series of ribs and series of nose openings provide a partitioned hollow structure that facilitates bullet penetration with proper mushrooming at the target.

The folded ribs and a like number of staves form. an uninterrupted continuation in an abutted array around the circumference at the hollow tip from jacket metal at its mouth originally of substantially uniform thickness circumferentially. Each stave or panel is flanged at its margins; and the staves are abutted at least at their flanges. There is preferably a necking-in and a longitudinal fracture only partially down each rib at the sharp bend to accomplish a pulling apart and a splitting between the contiguous flanges beginning at the edge of the jacket. Flanged slits preferably are formed in the jacket wall in each rib but only at the edge. The resulting flanged and abutted stave structure of the jacket edge provides desired tip as well as core support while permitting expansion with improved uniformity.

Splitting is achieved by an initial denting at evenly spaced points and a final severe working inwardly rather than by complete removal of part of the jacket edge or by any complex cutting and stretching operation.

The base jacket, to give further core support, is locked to the soft core by one or more cannelures involving knurls of the type shown in prior US. Patent 1,730,871, which provides an interior portion of the jacket of decreased diameter.

At the mouth of the jacket in the finished bullet, there are preferably six, marginal flanged, longitudinally as well as circumferentially curved staves not only integral with the rest of the jacket but also at least contiguous, if not integral as well with adjacent staves forming sectors of the hollow tip. Adjoining staves are buttressed and are largely interconnected by a tapering, pinch pleated, nose partition structure providing the greatest marginal fianging back of the edge of the base jacket but tapering to the least flanging at the ends of each stave, where each joins the rest of the jacket. The flanged staves curve inwardly to make the front end of the sharp point bullet.

ogive and the inward extension of each flange at the edge must exceed the thickness of the swaged jacket edge sufficiently to put the resulting evenly spaced ribs in contact around the central axis. The thickness of the base jacket material at the edge, which originally is in the range from about 0.010 of an inch to about from 0.015 of an inch for the small arms ammunition contemplated according to this invention, is uniformly increased at least in the staves by a necking action in forming the ogive. The pleated web radially, forming the ribs, and the staves together nearly close the hollow tip except for multiple openings at the nose of the fully jacketed bullet.

At very edge of the nose, all the jacket is in the abutted stave ends. Back of the aperture, where the ribs touch, the greater proportion of jacket is in the ribs and the lesser in the staves.

Six creases were found suitable usually for making the rosette hollow tip of this invention; these provide a hexafoil formation of the jacket mouth as shown in FIGURES 1 and 3. In practice the number of staves and pleated webs selected is determined by the jacket thickness, size of jacket mouth openings desired and the extent of bullet nose taper involved to give the necessary flanging, contacting, and hollow nose buttressing by the ribs.

By holding the hardness of the jacket to a minimum,

and/or by otherwise varying the metal thickness and de gree of infolding at the pleats, it is possible to reduce the sharpness of the bend somewhat and thereby avoid excessive pre-spliting at each reverse bend of the jacket While maintaining a stress concentration predisposing the jacket upon target impact to split uniformly along predetermined lines. This provides a variation in the degree of constraint offered the core making the jacket month more suitable for certain varieties of this type of hollow The soft core material provided in insufiicient to fill the jacket final finished to a rosette tip.

Since the jacket mouth openings at the rosette tip can be made very small, powdered core material can be employed as well as the usual solid slug of lead base metal, compressed in the jacket. When powdered lead is used, the degree of granulation and compression is varied to control the bullet density sought. By adjusting the density nearer that of the jacket, bullet unbalance from jacket thickness variation is minimized.

Because of necking-in of the jacket mouth, i.e. bending in of each stave, the entire edge of the base jacket at the nose is sloped rearwardly with respect to the axis of the bullet to provide an outwardly flared hollow ahead of the ribbed jacket edge including the substantially identically beveled or flattened leading edge of the pleated flange and rib forming webs. The slope is substantially at a right angle to the jacket curvature tangent.

Upon impact this rosette type of hollow tip provides a wedge action on the nose of the bullet to advantageously initiate the outward expansion of the jacket and core in all radial directions uniformly.

In the pleated region about a central opening, there is an abutted substantially double flange structure substantially thicker circumferentially than the greatest radial wall thickness of the adjacent sectors. In this region, the jacket metal is gradually deformed to create a tiny central opening and a circumferential array of as many small openings as there are ribs, extending radially.

In the embodiment of FIGURE 1, the bullet has a base jacket 1 from the'relatively flat, open edge 2 of which there recedes a nose hollow 7 formed by abutting ribs 10 extending over the nose portion 21 of the soft core 20. Bordering the nose there is relatively thin jacket portion 3 bearing the substantially full circular annular jacket edge 2 and on the outside of which there are longitudinally extending parting lines 8 indicative of the existence of an internal structure of uniformly distributed rather tightly closed pinch pleats. The lines are at the apex of tiny cusps at the edge 2 and taper away from it to a hairline.

Each pinch pleat rib 10 consists of a pair of flanges 11 and 12 which are integral extensions of the lateral margins of the staves 9. These are abutted internally along a line at which the flanges 11 and 12 are in contiguity at least adjacent their inner ends at which the flanges may be partially split from each other, however along only a very small part of the length at the inner end 13 of each pinch pleat rib 10. Therefore, the array of alternate ribs and staves form a continuous array of flanged jacket metal staves adjacent the jacket edge 2 and a multiplicity of hollow spaces 14 about a central opening 15 around which ribs 10 abut at 16.

At the edge 2 the thickness of each of the flanges 11 and 12 and thickness of the intervening staves 9 are substantially equal to make each internal rib 10 of about twice this thickness and to extend inwardly sufficiently to form a hollow point subdivided into openings 14 and 15. The mouth portion 3 of jacket 1 adjoins the thicker rear part 4 which is integral with the base 5 of the jacket. A knurl 6 forms a circumferential indentation in the thick circular cylindrical part 4 of the base jacket. Remotely from opening 15 and edge 2, each rib 10 becomes not only shallower but its web thicker and less flexed so that splitting by fracture occurs only at 13.

Back of the external hollow 7 and within ribs 10 is an internal hollow 17, forming a space between nose ribs 10 and the core front 21. Thus, the bullet core stress at the nose is reduced. Thus, the open point includes hollows 7 and 17, and ribs 10 making openings 14 and 15 which connect these hollows.

When the bullet of FIGURES l and 2 strikes its objective and has achieved substantial penetration, the flanged staves under rifling-induced rotation are twisted open and bulge outwardly to form curved scoop-shaped flutes and eventually splitting occurs from the tip all the way back between the flutes as the pleated ribs unfold. Finally continued bulging and the concomitant fracturing is further accompanied by a bending back or rearward furling of the staves 9 which at the heaviest impact will ultimately peel back the relatively thin front end 3 of the jacket until peeling is stopped at the thickened walls of the cylindrical jacket wall 4 adapted to take the rifling of the gun barrel.

In the embodiment having the tip of FIGURE 3, the bullet also comprises a base jacket 1 and a soft core 20, not shown. Adjacent the front edge 22 of the jacket there is a sharper bullet ogive than shown in FIGURE 2 and a plurality of pinch pleat ribs 19 which extend inwardly somewhat more deeply and form a series of pronounced splits 23 within the cusps in the jacket wall at the edge of the jacket. In the presence of more severe swaging, the apex 23 of each cusp is so severely bent that fracturing does occur more completely. This form of the bullet provides a smaller point by filling up more of the opening at the recesses 24 and 25 and flattening more at both 23 and 26.

In fabrication of the bullet in accordance with this invention, there is followed the procedure of cupping to make cup 101 from desired base jacket metal; assembling with a slug or particles of core material pressed within the jacket cup as shown in the apparatus of FIGURE 4 after pressing; an edge creasing to provide circumferentially spaced indentations 108 adjacent the open edge of the hollow nose cup-shaped product 1 10; and swaging the creased assembly of FIGURE 5 to finish the bullet shape at its nose.

The indentations are achieved with a pie-cut edge creaser shown in FIGURE 4 and having a circumferential array of radial directed fines corresponding in number to the number of pleats desired at the open end of the jacket. This sort of creasing turns in the open end of the jacket to form a rather frusto-conioal shape there having a circumferentially spaced series of edge flutes 109 and cusps 108,

at the latter of which the plea-ted ribs will be formed in the final swaging operation shown in FIGURE 6. According to the process of this invention there is provided sutlicient inward extension and thickness in the pleated region of the ribs to make a sufficiently severe bend and thereby achieve a predetermined line of preferential splitting without any jacket cutting or difiicult jacket drawing I to create grooves, indentations, or scallops.

As shown in FIGURE 4, the cup 101 has a posterior portion of greatest thickness adjacent its closed base and also a tapering anterior portion 103 terminating in the edge 102 of the open end of the cup.

In the cavity of die 30 there is a seating pin 31 upon which there is placed jacket cup 101 containing a compressed slug 120 of core material having a front end recessed adjacent the straight cup edge 102.

Thinness at 103 may be obtainable by a conical fiare terminating in an enlarged cylindrical portion adjacent the edge 102. Either of these types will provide a suitable thin front end 103 for making the ogival part 3 of the finished bullet jacket.

The cup is creased with a crimping die 40 having in its cavity 41 six radially arrayed equally spaced creasing fins 42. When the jacket cup edge 102 is thrust into cavity 41 by die pin 31, these fins crease the cup 101 at 108 until there is developed the intermediate foil shaped edge and flutes 1'09 shown in FIGURE 5. Knockout pin 32 ejects the intermediate product shown there.

The crimped assembly is then subjected to a further operation in a suitable female swaging die 50, the interior contour of which corresponds to the desired finished contour for the projectile at its nose and along its sides. As plunger 51 moves in during swaging, the circumference of the anterior portion 3 of the jacket 1 is reduced radially and the pleats 8 are formed to make the final finished sharply tapered point at the mouth of the jacket.

As a result of this operation, at this stage parting lines on the exterior of the open point jacket are discernible by the naked eye, inasmuch as they form external indentations in the jacket in the shape of cusps.

In the formation of stave-like sectors 9, the open edge 2 at the front end of the jacket is bent inwardly to slope the edge rearwardly to grip the soft core more snugly. Consequently, the tip of the jacket 1 does protrude beyond the unexposed nose 21.

The expansion action of the structure of this invention appears to be more uniform because of the combination of (a) edge unsupported paneling in the staves and (b) regular, thick and rather deep internal ribbing which notches the core, but not until after impact, which reinforcing the paneling longitudinally, intermediate the ends of the staves, and further (c) in combination with a short core, which may be a compressible compact of core particles. This minimizes erratic upsetting of the core all the way up to maximum impact because it gives a preferred variation in the tendency of the jacket to tear at regularly spaced intervals with the least initial resistance at the lowest velocities of impact and with the most final resistance at the end of impact at highest velocity.

At the lowest velocities of impact, the finished bullet because of the softness of the core, especially when compressible, and heavy ribbing provides pro-splitting with edge reinforcement and low resistance to upset needed at the very edge of the jacket. The hollow point with the flanged split offers the least resistance to expansion on account of accordian action while at the same time offering desired but momentary delay in expansion in the initial circumferential confinement to the expanding core on account of the flanging. Thus, expansion occurs readily even at distant ranges where the energy is considerably spent and the velocity low, but with a sharp hollow tip premature mushrooming is avoided to allow suflicient penetration of the bullet to occur first. The central edge of the relatively heavy double ribbing being radially deeper than the rest of the flange to define hollows improves the delaying action.

As the severity of impact is increased, a desired continuation and increase of resistance is offered because the part of the jacket pleat-s coming into action becomes shallower b-ut broader so that at each stage the web there will not open initially between the moving staves but will continue to offer confinement to the upsetting core until the required unfolding followed by complete splitting occurs. Wherever the pleated rib is finally split, progress of the split becomes more difficult as the ribbing tapers away and the degree of metal stressing and hardening at the bend decreases, whereupon the increasing bulk of expanded core material continues to encounter support and guidance as the staves open outwardly and finally furl back with increasing resistance.

This invention is an improvement over expanding bullets made according to US. Nos. 1,062,865; 2,321,344; 2,327,- 950; 2,765,738; and 2,838,000.

What is claimed is:

1. The process of making a jacketed expanding bullet having a soft metal core comprising the steps of (a) forming an elongated open mouth relatively hard jacket,

(b) placing a core of relatively soft metal into said jacket so that the mouth of jacket protrudes ahead of said core,

(c) radially creasing the mouth of said cup partially ly inward along circumferentially evenly spaced lines which extend longitudinally,

(d) contracting said creased mouth to an ogivally shaped sharp nose and hollow point including folded ribs extending longitudinally and radial-1y into abutment with adjacent ribs in said nose and dividing said point about its center into a plurality of apertures.

2. The process of claim 1 including charging the jacket with particles of core metal.

3. The process of making a jacketed expanding bullet having a soft metal core comprising the steps of (a) forming an elongated cup of relatively hard metal including a base and an open mouth,

( b) longitudinally pressing a core of relatively soft metal into assembly within said jacket adjacent said base so that said mouth protrudes ahead of said core,

(0) radially creasing the mouth of said cup partially and uniformly inward along a plurality of circumferentially evenly spaced lines intersecting the edge of said mouth and longitudinally extending toward said core to a point adjacent said core,

(d) swaging said cup to con-tract said creased mouth uniformly to an ogivally shaped sharp nose and hollow point including external staves and internal folded ribs extending longitudinally and radially into abutment with adjacent ribs in said nose and dividing said point about its center into a plurality of apertures within said staves and about a central aperture.

4. The process of claim 3 including charging the cup with particles of core metal before pressing.

References Cited by the Examiner UNITED STATES PATENTS 2,765,738 10/1956 Frech 29-123 3,136,052 6/1964 Pickart 291.23XR

RICHARD H. EANES, JR., Primary Examiner.

Claims (1)

1. THE PROCESS OF MAKING A JACKETED EXPANDING BULLET HAVING A SOFT METAL CORE COMPRISING THE STEPS OF (A) FORMING AN ELONGATED OPEN MOUTH RELATIVELY HARD JACKET, (B) PLACING A CORE OF RELATIVELY SOFT METAL INTO SAID JACKET SO THAT THE MOUTH OF JACKET PROTRUDES AHEAD OF SAID CORE, (C) RADIALLY CREASING THE MOUTH OF SAID CUP PARTIALLY LY INWARD ALONG CIRCUMFERENTIALLY EVENLY SPACED LINES WHICH EXTEND LONGITUDINALLY, (D) CONTRACTING SAID CREASED MOUTH TO AN OGIVALLY SHAPED SHARP NOSE AND HOLLOW POINT INCLUDING FOLDED RIBS EXTENDING LONGITUDINALLY AND RADIALLY INTO ABUTMENT WITH ADJACENT RIBS IN SAID NOSE AND DIVIDING SAID POINT ABOUT ITS CENTER INTO A PLURALITY OF APERTURES.

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