US1757584A - Shot shell - Google Patents

Description

y 1930 J. M. QLIN 1,757,584

SHQT SHELL OriginalFiled Oct. 6, 1923 8000 Hz BARREL TIMES WITH LOADS L/5TED BELOW z 'WZ/Y 122' 002905 STAND/7RD .00z445 55c.

- ZZ LIZ" I U 6 000 E H X/ PRESSURE/9T SEVERAL POSITIONS ALONG BARREL, v POSITIONS-IN HAHN GUN A B c E F 0 I 36 6/2. OZ. #65H. H036 7405 10/5 19/3 1400 N20 I 26.5 M506 7054 2023 1902 1400 H04 m 12f J 0R5. /0370 0/55 2722 I000 I427 //90 E 55 SR. 0042 8/65 2040,2012 /40z I204 5000 c: D u v Q 5000 CL INCHES mo/w BASE 0F SHELL T0 PISTON. 0 1 +|B 1 i 1 I 1 |F| 0 7 I5 fife/273% c707//r/%0z//x fla fiAVfa/xg Patented May 6, V 1930 UNITED STATES PATENT OFFICE JOHN M. OLIN, OF ALTON, ILLINOIS, ASSIGNOR TO WESTERN CARTRIDGE COMPANY, OF EAST ALTON, ILLINOIS, A CORPORATION OF DELAWARE i snow SHELL Application filed October 6, 1923, Serial No. 667,075. Renewed November 9, 1925.

This invention relates to cartridges and more particularly to shot shells adapted for use in shot guns.

The barrel of a shot gun should be light, especially at the forward part, in order that the weapon may be easy to handle. Moreover even at the breech the barrel cannot be as heavy as in a rifle, when the relative bores are considered, since shot guns are of considerably greater caliber than rifles. Accordingly the powder charge in a shot gun shell is necessarily limited by the limiting breech pressure, that is, the pressure that can safely be developed at the breech, which for an ordinary twelve gauge gun is about twelve thousand pounds per square inch.

In a shot shell the propellant charge is confined by wadding, over which is placed the charge of shot, and the latter is in turn confined by its covering wad and the turned over end of the paper shell, while a primer is provided in order to ignite the powder. The wadding does not, however, form a tight seal, as does the bullet in a rifle; accordingly heretofore a quick burning powder has been used a which may become consumed at'the time or even before the charge leaves the shell. In other words the major part of the work was applied to the charge at the breech during the initial stage. This was necessary because of the relatively large diameter of the gun bore and the fact that on account of the lack of an efiicient seal, the pressure could not be maintained along the gun barrel, as is a necessary condition to the use of a slow burning powder. Accordingly where high velocities were required, 'largeror over charges of powder were necessary; these charges and, therefore,

the velocity were however limited by the limiting breech pressure.

As a result of the above described conditions the powder charges of shot shells have been limited to quick burning powders, for the use of slow burnin powders has invariably resulted in irregu ar and erratic ballistics and in much unburned powder. The use of condensed or dense mtro-cellulose powders, if

the grains are too large resulted in uncertainty of ignition; and even if ignited the grains would not be wholly consumed. If, on the the velocities are limited by the limiting breech pressure, and any attempt to increase these velocities, even within quite narrow limits, will result in dangerous pressures. It

should be remembered-thatinthe manufacture of shot shells, the powder is measured and not weighed; accordingly where the powder is not uniform in its subdivision and action the results are liable to not only be uncertain and erratic, but the resulting pressure are liable to be dangerous. For the above reasons a dense nitro-cellulose powder, when suificiently subdivided to enable it for use in a shot shell, is not satisfactory.

The burning action of dense nitro-cellulose powder is oftenaccelerated by the addition of nitro-glycerine, or even by the addition of black powder or other ingredients. These powders, however, as well as the bulk smokeless powders, are all of the same general type and are directed towards the same end, namely to produce a propellant charge which will burn quickly and may be almost consumed at the initial stage. In none of the shot-gun shells as heretofore constructed and loaded, is the maximum pressure developed or sustained for any appreciable distance along the gun barrel, but the initial pressurev drops rapidly to its minimum. Accordingly the total-energy utilized is practically that released upon the initial combustion of the charge.

The employment. in a shot shell, of a .powder in which the pressure rises so rapidly to a maximum is that the wadding and the mass of shot in front thereof are started so suddenly that the movements imparted to the various shot. of the charge are unequal; ac-

cordingly the shot travel at unequal and un uniform velocities towards the target; this results in stringing of shot, which in actual practice may be so great as to greatly aiiect the effective accuracy on hitting .a target moving across the line of flight of the shot.

One of the objects of this invention, therefore, is to provide a shot shell containing'a propellant charge of a granular dense smokeless or nitro-hydrocarbon powder, and more particularly, a dense colloided nitro-cellulose powder, which is in such form and so confined as to burn progressively when fired in a shot gun, so that the combustion continues for an extended distance along the gun barrel.

Another object is to provide a loaded shot shell wherein the propellant charge consists of progressive burning smokeless powder which is adapted to sustain a nearly uniform pressure while the shot charge moves out of the shell.

Another object is to provide such a loaded shot shell in which the progressive burning smokeless powder propels the shot shell with a material reduction in the stringing of shot as compared to shells using standard smokeless powder.

Further objects will appear from the detail description taken in connection with the accompanying drawing, in which:

Figure 1 is a section of a shot shell embodying this invention; 1

Figure 2 is a pressure diagram illustrating the action as compared to others of the prior art; and

Figure 3 is-a comparative barrel time diagram. 1

Referring to the accompanying drawing,

and more particularly to Figure 1, 1 designates a shell, which as shown is of paper, has a metallic base 2, and a base wad 3. A battery cup t of any suitable construction forms a primer cavity in which is arranged an anvil 5 cooperating with the priming composition, while the partly empty primer cavity has a flash hole as shown. The propellant charge is shown at 6 and is confined by wadding 7, over which is the shot charge 8 confined by the shot wad 9 and the crimped end 10 of the shell.

The propellant charge preferably consists of dense colloided nitro-cellulose powder; this powder is however progressive, and in accordance with one embodiment of this invention the powder grain is surface treated so that the surface layer of the grain is modified in order to cause the outer layers to burn more slowly under the same conditions than the dense colloided nitro-cellulose core. The powder is, however, so modified that it will burn completely, but progressively, under the conditions present in a shot gun when the shot shell containing that propeller is tired; accordingly the powder is so subdivided and surface treated as to meet these conditions.

The propellant charge is confined in the shell by the wadding. This wadding is, how'- ever, heavy or thick so as to not only confine the charge initially, but so as to also seal the bore sufliciently that the required pressure is sustained for a sufficient extent along the barrel in order to effect complete combustion of the charge. The primer is moreover a hot primer so as to generate a sufficient volume of flame in order to fully ignite the powder. The powder itself is also of suflicient fineness as to be not only properly ignited by the primer but so that-the required pressure and temperature will be maintained to maintain the combustion.

Now the heavy wadding would ordinarily required a longer shell; however, in view of the fact, as will hereinafter appear, that long base wad is not required, the standard bulk powder base can be used; this in connection with the smaller volume of the powder charge, permits the employment of the required heavy wadding in a standard shell with a shallow or short bulk powder base.

A practical example of an embodiment of this invention will now be described; it is understood, however, that this invention is not limited to this particular example, but that various modifications may be made without departing from the essential features of this invention.

The drawing shows the proportions of a twelve gauge shell, containing,for example, a four-tenths (0.4) grain primer of fulminate of mercury, potassium chlorate and antimony sulphide. The wadding may be of felt or any other suitable material, while the base wad corresponds in this particular embodiment to that of a standard bulk powder base.

The powder charge consists of dense coll-oided nitro-cellulose, which can be made in any usual or suitable manner well known to those skilled in the art. This powder is then granulated or subdivided, by cutting or grinding in any suitable manner, so that it will pass a thirty mesh screen. This powder is then surface treated in any suitable manner so as to render it progressive burning. As a practical example the treating agent is a deterrent such as dinitro-toluene, which can be applied in the usual manner, as by rumbling in a rotating drum, at a temperature of about C. for about one-half hour using about two percent of the agent relative to the weight 01 the powder; so that the powder grains will each become impregnated with the treating agent. The object is to subdivide the powder to an extent suficient, and to impregnate each powder grainto an extent sufficient, as to cause the powder when confined and primed in a loaded shot shell as previously described, to burn progressively when fired in a shot gun. F or a twelve gauge 'shell', the powder charge is from 35 to 40 grams and this will have a volumetric density use of a heavy wadding as previously de scribed.

The action of a shell embodying this invention is striking and is strikingly illustrated in Figure 2, as compared to shells using other smokeless powders. Thus I is the pressure curve of a twelve gauge shell containing Walsrode powder, i, e., a pure uncoated dense colloided nitro-cellulose powder; II is the pressure curve of a corresponding shell containing (Infallible) a nitro-cellulosenitro-glycerine powder; III is the pressure curve of a corresponding shell containing bulk smokeless powder; while IV is the pressure curve of a corresponding shell embodying this invention. In this figure the points were developed by pressure readings at successive points along the barrel of a shot gun, measuring from the breech. Figure 3 further shows a' comparison of the barrel times of the corresponding shells whose pressure curves are shown in Figures 2, the standard being a definite standard and staple smokeless powder used for checking purposes; the barrel time was measured by determining the time interval in seconds between the fall of the hammer until the charge of shot emerged from the muzzle of the gun. .The gun used was a twelve gauge gun having a full choked barrel of a length of twenty-nine and onehalf inches.

It willbe seen that in the loaded shot shell embodying this invention, the progressive burning smokeless powder develops and. sustains a pressure which propels the shot charge gradually out of the shell and'for an extended distance along the gun barrel, with a material increase in barrel time as compared to sh ls usin standard smokeless powder.

pon re erence to Figure 2, it will be seen that while shells I, II and III develop a high initial pressure dropping rapidly, shell IV develops-not only a very much lower initial pressure, but this initial pressure is maintained nearly uniform while the shot charge moves out of the shell (whose length for twelve gauge is from two and one-half to two and three-fourths inches) and even after the shot charge has moved out of the shell. In fact the pressure developed by the progressive burning powder is maintained nearly uniform for a considerable distance along the gun barrel and even thereafter is maintained above the corresponding pressures of the other shells. Accordingly the progressive burning powder is adapted to develop and sustain a ressure which starts the shot charge gradually out of the shell and propels the same gradually through an exten ed dist-ance along the gun barrel. It will also be noted that the area bounded by curve IV is substantially equal to those bounded by any of the other curves I, II or III. To still more.

strikingly illustrate the comparison, curve V has been developed from curve IV by making the initial pressure of IV equal to the initial pressure of I. The area bounded by curve V is, of course, much greater than that bounded by any of the other curves I, II or III.

The striking different characteristics of the shot shells embodying this invention and those of the prior art are believed'to be due to the following A powder charge in a shot shell starts to burn from the outer surfaces of the individual grains while suflicient pressure is being built up to overcome the inertia of the shot charge and start it; the combustion then continues to the centers of the grains as the shot charge moves along the barrel. It is, therefore, clear that in the shells of the prior art (I, II, III,) the maximum pressure must be developed before the shot charge has moved any appreciable distance or has even moved out of the shell; accordingly, the pressure will drop very rapidly as the shot charge moves along the barrel. Where, however, the powder charge in a shot shell embodying this invention is progressive burning, as by coating or impregnating the powder grains with a deterrent, then the initial combustion rate is retarded substantially and sufliciently to develop its maximum pressure an extended distance along the gun barrel so as to sustain a nearly uniform pressure while the shot charge moves out of the shell. This is due to the fact that the combustion of the grains and at the surfaces thereof will be retarded so that the shot charge is started on its course at a lower pressure, while the maximum pressure is developed and sustained for an extended distance along the gun barrel; this latter is due tothe increased rate of combustion of the powder grains after the coating or impregnation has been consumed. That this action takes place is clear fromcurve IV. The factors of granulation, coating or impregnation, etc., must, however, have special reference to the conditions encountered in a shot gun as distinguished from the conditions encountered in a rifle as herein explained.

This diagram, therefore, shows that in the shell embodying this invention, not only is the same energy released and imparted to the shot, but at a much lower maximum pressure than with the shells of the prior art; accordingly the breech pressure is not only considerably lower under the same conditions, but for velocities towards the target.

tained thereafter at a hi her value, the shot charge will be more gra ually and therefore more uniformly accelerated. This latter point is additionally borne out by the material increase of the barrel time as noted in Figure 3. In accordance with this invention, not only is the muzzle velocity and therefore the range materially increased, but I the stringing of the shot is materially reduced, while the pattern is materially improved; this is due to the more gradual rise of pressure and the more uniform acceleration imparted to the shot charge. The comparatively gradual rise of pressure causes the wadding and the mass of shot in front thereof to be started gradually; accordingly the movements imparted to the various shot of the charge are more nearly equal so that the shot travel at more nearly equal and uniform The reduction of the stringing of the shot results in the attainment of greater accuracy in hitting a target, especially when moving across the line of flight of the shot. Actual tests show that the effective range is increased by more than twenty yards, for long range shooting, while the pattern is materially improved and the stringing of the shot is reduced by one half, as compared to other shells. Furthermore in the shell embodying this invention, a given charge of shot (such as 1 1; ozl, Figure 3) can be propelled a greater distance with a given propellant powder charge as compared to other shells; accordingly a greater shot charge can be projected the same distance. The desired results, namely, the higher velocity, closer pattern, less shot stringing and longer reaching results are however accomplished without increase but rather with decrease of breech pressure, due to the fact that the combustion continues along an extended part of the gunloarrel, rather than within a short distance and within the breech.

These results are accomplished by the employment of the combination of elements embodied in the shell as described. The powder being of granular form, is subdivided to an extent sufiicient so as to not only be initially ignited, but so that the required pressure and temperature will be maintained to maintain the combustion. The surface treatment of the dense colloided nitro-cellulose powder not only retards the initial combustion and therefore permits the pressure to build up gradually, but this modification of the surface permits the subdivision to be oarried to the desired fineness so that the grains will be properly ignited by the primer under the conditions encountered in a shot shell, when the powder charge is confined by the wedding. This surface treatment moreover renders the ignition more regular and uniform, even if the grains vary somewhat in size, due to the fact that the retarding efi ect tends to make the ignition of difi'erent sized grains more nearly the same than where the dense colloided nitro-cellulose' is left untreated. Accordingly different shells of the same gauge will readily give the same results, which is so desirable and even necessary.

Upon ignition ofthe charge by the hot primer, the powder grains will become ignited, especially since they are confined by the heavy wadding. Such confinement will, however, cause the pressure to buildup, although the initial pressure is much less than where untreated powders are used. Accordingly the pressure will be sustained as is necessary for the continued combustion of the dense colloided nitro-cellulose. As now the burning proceeds through the impregnated surface to the dense colloided nitro-cellulose core, therate of combustion will increase so that the desired pressure is maintained, espe cially since the heavy wadding provides sufficient resistance to the expansion of the gases to maintain the pressure. The result is, therefore, that the combustion is uniformly accelerated, even after the confining wadding and the shot begin to move so that the pressure is sustained nearly uniform for an extended distance along the gun barrel; the result is that the shot charge is uniformly accelerated under a lower initial pressure sustained for an extended distance along the gun barrel.

It will, therefore, be seen that the final result is due to a combination of factors found in the shell embodying this invention. The small bulk of the propellant charge permits the use of heavy wadding, thereby forming a good gas seal and accordingly more resistance to the expansion of the gases. The employment of a hot primer and the great resistance of the confining wadding enables a surface treated or progressive dense colloided nitrocellulose powder to be used. The surface treatment enables the powder grains to be subdivided to an extent sufficient to permit such ignition under the conditions encountered in a shot shell, while this treatment further makes the ignition of the grains uniform and reliable. The ordinary non-progressive dense colloided intro-cellulose powder as here= tofore employed in shot shells, under similar conditions would produce dangerous breech pressures, while the progressive powder burns in such a manner that the pressure is distributed over a large area, thus reducing the pressure per unit of area and also reducing the amount of energy used in overcoming the inertia of the shot charge. This conserved energy acting on the moving charge and the uniform acceleration imparted thereto increases the velocity.

While the best results have been obtained by the combination of elements in a shot shell as heretofore described, in which a propellant charge is a dense colloided nitrocellulose,

. suitably subdivided and surface treated, it

' erin powders do not burn progressively, as-

has been previously described, they can be made or treated so as to burn progressively. This can be accomplished by so incorporating with the nitro-cellulose and nitro-glyc-' erin, preferably during the course of manufacture, a cooling or slowing agent having the action of reducing the temperature of burning and slowing up the combustion in such a manner as to produce the desired result. There are many compounds which may be used for this purpose, most of which are exothermic, among them being: Vaseline and similar products, alkaline bi-carbonates, either alone or mixed with Vaseline, diethyl diphenylurea, dimethyl diphenylurea, cyanamide, tartrates, olive oil, castor oil, fats and reslns, soaps, oxalates, starch, dextrme, and

. diphenalamin. Such nitro cellulose nitroglycerin powders, containing from 35% to 40% of nitr'o-glycerin, together with a cooling or slowing agent, may be surface treated as heretofore described in order to still further enhance their progressive burning action in a shot gun.

It is further obvious that various changes may be made in details without departing from the spirit of this invention; it is, therefore, to be understood that this invention is not to be limited to the specific details shown and described.

Having thus described the invention, what is claimed is:

- 1. A shot shell containing a primer, a propellant charge of granular smokeless powder,

a shqt charge and wadding between the propellant and shot charges, the powder being subdivided to an extent suflicient and containing a deterrent but sufliciently primed and confined so as to burn progressively when qfired in a shot gun.

2. A shot shell containing'a primer, a propellant charge of granular dense smokeless powder, a shot charge and wadding between the propellant and shot charges, the powder being subdivided to an extent s'uflicient and treated with a deterrent but sufiiciently primed and confined "so as to burn progressivegf/kwhen fired i9 a shot gun.

3 shot shell containing a propellant charge of granular dense colloided nitro-cellulose powder, a shot charge and heavy wadding between the propellant and shot charges,

the powder beingsubdivided to an extent suflicient and treated with a deterrent but sufliciently rimed and confined so as to burn progressive y when fired in a shot gun.

' 4. A shot shell having a bulk powder base and containing a comparatively small bulk propellant charge of granular dense colloided nitro-cellulose powder, a hot primer, a shot charge and heavy wadding between the propell'ant and shot charges, the powder being subdivided to an extent suflicient and treated with a deterrant but sufliciently primed and confined so as to burn progressively when fired in a shot gun.

5. A shot shell containing a propellant charge of anular pro 'essive burnin smokeless po v den'a' shot harge and wad ding between the pro ellant and shot charges, the powder being s ciently primed and confined and having its initial combustion rate retarded sufliciently to sustain a nearly uniform pressure through an extended distance along the gun barrel after the shot charge has moved out of the shell.

6. A loaded shot shell containing a primer, a shot charge, wadding and a shot propelling charge of granular progressive burning smokeless powder whose initial combustion sufiiciently primed and confined so as to burn progressive y when fired in a shot gun.

7. A loaded shot shell containing a primer, a shot charge, wadding and a shot propelling charge of granular progressive burning smokeless powder whose initial combustion rate is retarded suflicientl and which is sufficiently primed and con ed to develop its maximum pressure and sustain the same an extended distance along the barreh In testimony whereof I a my signature this 23rd day ef August, 1923.

1 JOHN M. OLIN.

rate is retarded substantially, and which is

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