Historical Document · 1972
Theodor Koch's polygonal-rifling patent (continuation of 26 September 1967; issued 22 February 1972). The HK PSG1 dive cites it for the H&K polygonal barrel.
United States Patent [151 3,643,364 Koch [451 Feb. 22, 1972 [541 RIFLED GUN BARREL WITH THE INTERIOR CROSS-SECTIONAL CONFIGURATION DEFINING A FOREIGN PATENTS OR APPLICATIONS 257 REGULAR CURVILINEAR POLYGON [72] Inventor: Theodor Koch, 7238 Obemdorf, (Neckar), Lehenhofweg 29, Germany [22] Filed: 1/1864 Great Britain ........................... ..42/78 3,068 12/ 1860 3,166 12/1861 Great Britain ........................... ..42/78 Great Britain ........................... ..42/78 Primary Examiner-Samuel Feinberg Assistant Examiner-C. T. Jordan Nov. 7, 1969 [57] [21] App1.No.: 871,624 ABSTRACT A ri?ed barrel intended for use with small arms, particularly in Related US. Application Data [63] Continuation of Ser. No. 670,654, Sept. 26, 1967, , abandoned. combination with steel-jacketed softcore ammunition having no special rotating bands provided on the exterior thereof, which barrel has a cross-sectional con?guration such that the, interior surface of the barrel de?nes a regular polygon with rounded sides and corners, which corners form the ri?ing in the barrel wall and represent arc segments spaced uniformly about the interior surface and having a common radius of cur vature, the rounded sides of the polygon extending between References Cited the rounded comers and representing arc segments having a common radius of curvature of lesser magnitude than the ?rst UNITED STATES PATENTS mentioned radius of curvature, the transitional regions [56] 9,830 7/1853 Lancaster .......... ..42/78 1,275,028 8/1918 Holter . . . . . . . . . . 1,335,444 3/1920 Lashley .................................... ..42/78 between adjacent arc segments having different radii of curva ture being continuous. . . . ..42/78 9 Claims, 1 Drawing Figure 1 3,643,364 RIFLED GUN BARREL WITH THE INTERIOR CROSS SECTIONAL CONFIGURATION DEFINING A REGULAR CURVILINEAR POLYGON This is a continuation of Ser. No. 670,654 ?led Sept. 26, 1967, now abandoned. The invention relates to a ri?ed barrel intended and suitable in particular for small arms using as ammunition bullets without any special rotating bands. ’ In conventional ri?ed barrels the inside of the barrel is pro vided with internally projecting lands equally spaced along its 2 core takes in a conventional ri?ed barrel under the pressure of the lands acting on the jacket of the bullet. This ensures that the bullet completely ?lls the barrel right from the start so that maximum advantage is taken of the action of the gunpowder gases while an increased wear of the barrel from gases escap ing between the bullet and the wall of the barrel is precluded. In addition, the bullet is properly seated over the full length of the barrel, a fact, which also favorably in?uences the ?ring ef ?ciency. At the same time, the deformation energy required to make the cross section of the bullet ?t the cross section of the circumference, said lands forming part of an extended spiral barrel is far less than the energy that would be required to twist about the longitudinal axis of the barrel. The rifles of completely ?ll the grooves and lands of conventionally shaped known construction have their barrels provided with a plurali barrels, which is, for instance, possible with a hard~core bullet, ty of such lands, the clearance between said lands being less because the chosen form of the barrel cross section cor than the diameter of the bullet, thus causing the lands to dig - (It responds to the natural deformation of the bullet when ex into the material of the bullet and producing a kind of tracks posed to the same radial pressures at a plurality of points in the jacket of the bullet in which the bullet seats against the equally spaced along its circumference. By a proper choice of lands, a rotary motion being imparted to it by the twist of said the smallest and greatest radii of the barrel and the form of the lands. transitions between these radii it can be ensured that the cross In order to fully utilize the impact of the gunpowder gases 20 on the bullet it is desirable that the bullet perfectly ?t the cross section of the barrel and that no gunpowder gases can escape from the barrel past the bullet. However, detailed investiga tions have shown that the lands will not dig into the jacket of section of the barrel has the same area as the circular cross section of the undeformed bullet so that the bullet de?nitely ?lls the barrel completely. In a preferred embodiment of the invention the cross sec tion of the barrel has the form of a circle ?attened at four the. bullet to an extent where the jacket of the bullet would 25 points spaced 90° apart from each other, thus corresponding make full contact with the wall of the barrel in the area of the grooves. to the widely used conventional barrels with four grooves. The accompanying drawing shows a cross section through a Conditions are particularly unfavorable in the aft portion of barrel according to the invention. It will be noted, that the the barrel where the material of the barrel is exposed to the high gas pressure and the greater heat. Expansion measure 30 cross section through the interior of the barrel 1 deviates only slightly from the form of a circle inasmuch as the circle 2, ments and calculations have revealed that the gas pressure represented by the dash line and having the radius R, is flat may produce an enlargement of about 0.03 to 0.04 mm. and tened at the four points 3 offset 90° against each other. Con that an enlargement of the same order may result from the sequently, the distance r of the cross section of the barrel is heat. This enlargement grows in size as the load increases with the rate of ?re. Owing to the overall enlargement of the barrel 35 slightly smaller at these points than the radius R of the circle 2. At the same time, the distance r is smaller than the radius of a it may happen that in the initial portion of the barrel the bul let, rather than following the twist of the grooves, skips the grooves, being caught by them only after reaching the forward corresponding bullet, while the distance R is greater than the low spaces of roughly comma-shaped cross section on either contour of the cross section of the barrel blends in a continu ous line without any point of in?ection into the areas forming the grooves, which are located adjacent to the points 5. It is obvious that without any great expenditure of energy a bullet can be brought into the shape of the cross section of the barrel radius of the bullet. The transitions 4 between the points 3 portion of the barrel‘where the heat is less intense and the gas 40 where the distance of the barrel from the center of the circle is r and the points 5 with the distance R from the center of circle pressure is lower. However, even in that portion of the barrel 2 is such that the cross section of the barrel has essentially the the lands will not fully cut into the jacket of the bullet and the same area as the cross section of the corresponding bullet. It bullet will not seal the barrel completely. At best, the jacket of will further be noted that from the areas adjacent to the points the bullet seats against the wall of the barrel in the forward portion of the barrel in the middle of each groove, leaving hol 45 3, which correspond to the lands of conventional barrels, the side of the point of contact, which still permit the gunpowder gases to escape. The conditions just described, apart from causing a reduc tion in the speed of the bullet on account of the poor seal 50 so as to completely fill said cross section while a proper seat~ which it makes in the barrel as compared with the maximum ing is achieved in addition. This means that with a given gun speed that can be obtained and a reduced accuracy of ?re on powder charge the muzzle energy of the bullet is increased, account of the late seating of the bullet, also result in a much the seating is improved, and, ?nally the wear of the barrel is higher wear of the barrel. The hot gunpowder gases escaping through the narrow gap between the bullet and the wall of the 55 reduced. As the barrel according to the invention in its interi or has no edges extending along its longitudinal axis it is much barrel transfer an increased amount of their heat to the barrel, better suited for the application of a protective coating such as thus causing the wall of the barrel to be prematurely damaged. chrome than the known barrels with conventional pro?les. The conditions discussed occur in a particularly high degree In the same manner as the ri?ed barrels of known construc with tombac-clad steel-jacketed bullets with a soft core, as the soft core of such bullets is unable to produce the counterpres 60 tion, barrels according to this invention can be manufactured with the aid of a drift punch having a cross section which cor sure that would be required to make the lands cut into the responds to the internal cross section of the barrel. Naturally, steel jacket and instead yields to this pressure so that the bullet the invention is not restricted to the type of cross section is deformed as a whole without an optimum seal of the barrel and an optimum seating of the bullet being accomplished. shown in the accompanying drawing and, in particular, in It is the object of this invention to avoid these disadvantages 65 cludes forms in which the number of grooves differs from the four grooves of the embodiment shown by way of example. of conventional ri?ed barrels. According to the invention this Having thus fully described our invention, what we claim as object is achieved by an arrangement in which the concave new and desire to secure by Letters Patent is: surfaces of the lands along the circumference of the bore of the. barrel-concave as viewed from the axis of the barrel 1. ln a gun, a ri?ed barrel having a cross sectional con?gura blend into the areas forming the grooves in a continuous line 70 tion such that the interior surface of the barrel de?nes a regu without any point of in?ection so that the cross section of the lar curvilinear polygon with rounded sides and rounded cor barrel essentially takes the form of a polygon with rounded ners, said rounded corners being uniformly spaced about said corners and sides. This means that according to the invention interior surface and being formed by ?rst arcuately shaped the cross section of the barrel is given approximately that segments, each of which has radii of curvature smaller than shape which a tombac-clad steel-jacketed bullet with a soft 75 the distance of the corresponding point of the surface of such 3 3,643,364 4 segment from the longitudinal axis of the barrel, said rounded sides extending between said rounded comers and being formed by second arcuately shaped segments, each of which has radii of curvature greater than said ?rst mentioned radii of ment comprising a ri?ed barrel having a cross-sectional con ?guration such that the interior surface of the barrel de?nes a regular curvilinear polygon with rounded sides and rounded corners, said rounded corners being uniformly spaced about curvature and greater than the distance of the corresponding point of the surface of such segment from the longitudinal axis of the barrel, and the transitions between adjacent arcuately said interior surface and being formed by first arcuately shaped segments, each of which has radii of curvature smaller than the distance of the corresponding point of the surface of shaped segments being continuous substantially without any point of inflection and being formed by curved surfaces of substantially continuously changing radii of curvature, and 10 such segment from the longitudinal axis of the barrel, said rounded sides extending between said rounded corners and projectiles for use in said gun, said projectile being of the being formed by second arcuately shaped segments, each of said barrel as said projectile is subjected to radial pressures at a number of points on the exterior surface thereof correspond jacent arcuately shaped segments being continuous substan which has radii of curvature greater than said ?rst mentioned jacketed core type and having a substantially round cross sec radii of curvature and greater than the distance of the cor tion and being devoid of rotating bands on the exterior surface responding point of the surface of such segment from the lon thereof, whereby the cross section assumed by each 18 projec tile as it passes through said barrel, conforms closely to that of 15 gitudinal axis of the barrel, and the transitions between ad tially without any point of in?ection and being formed by curved surfaces of substantially continuously changing radii of curvature, whereby the cross section assumed by each projec ing to the number and spacing of said rounded sides of said cross section of said barrel. 2. The combination according to claim 1, wherein said cross section of said barrel de?nes a circle ?attened at four points tile as it passes through said barrel, conforms closely to that of said barrel as said projectile is subjected to radial pressures at a number of points on the exterior surface thereof correspond ing to the number and spacing of said rounded sides of said cross section of said barrel. angularly spaced apart at intervals of about 90°. 3. The combination according to claim 1, characterized in that the rounded sides and rounded corners alternate with one another. 7. The combination according to claim 6, characterized in 25 that the rounded sides and rounded corners alternate with one 4. The combination according to claim 1, characterized in another. ' that the arcuately shaped segment pass over into one another 8. The combination according to claim 6, characterized in in a continuous line substantially devoid of angles and points that the arcuately shaped segments pass over into one another of in?ections constituted by abrupt and relatively large changes in the radii of curvature thereof. 5. The combination according to claim 1, characterized in that the cross sectional area of polygonal con?guration of the in a continuous line substantially devoid of angles and points of inflections constituted by abrupt and relatively large changes in the radii of curvature thereof. barrel is substantially equal to the circular cross section of the 9. The combination according to claim 6, characterized in projectile to be used. that the cross sectional area of polygonal con?guration of the 6. In a breech-loaded gun using projectiles of the jacketed 35 barrel is substantially equal to the circular cross section of the projectile to be used. core type with a substantially round cross section and devoid of rotating bands on the exterior surface thereof, the improve 40 45 50 55 60 65 75