Patent Application
20120234199
The present disclosure relates to rounded cubic shot and to shotshells loaded with rounded cubic shot.
This section provides background information related to the present disclosure which is not necessarily prior art.
While the shot used in shotshells is conventionally spherical, a wide variety of shapes have been used (U.S. Pat. Nos. 3,877,381 and 4,913,054), including for example discs (U.S. Pat. Nos. 5,648,637 and 6,161,482), cubes (U.S. Pat. No. 4,982,666), needles (U.S. Pat. Nos. 4,996,923 and 5,325,786), pyramids (U.S. Pat. No. 4,686,904), cylinders (U.S. Pat. No. 2,343,818), flattened spheres (U.S. Pat. No. 3,952,659), belted spheres (U.S. Pat. Nos. 5,020,438 and 5,527,376), dimpled spheres (U.S. Pat. No. 4,173,930), tear drops (U.S. Pat. No. 4,718,348), and flechettes (U.S. Pat. Nos. 1,195,107, 3,444,813, and 3,599,568), and even mixtures of sizes (U.S. Pat. Nos. 41,590, 1,277,810, 1,575,716, 1,883,575, 3,074,344, 3,131,634, 3,598,057, and 3,796,157, 4,760,793, and 6,202,561) or shapes (U.S. Pat. Nos. 1,583,559, 3,996,865, 4,823,702, 4,982,666, and 7,607,393, and U.S. Application 20090114113).
However, these shot do not provide the ease of manufacturing, the projectile type, the projectile pattern, or the packing densities advantageously provided by various embodiments of this invention.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
Prior U.S. Pat. No. 3,952,659, incorporated herein by reference, discusses a flattened spherical shape that is “characterized as standard spherical shot which has been reformed to include six equally spaced, substantially flat faces,” and said flat faces “separated from each other by spherical portions.” The shot of the preferred embodiment of the present invention is essentially a cube shape with rounded edges and corners. The rounded edges and corners are preferably nearly tangential with the generally square, flat faces that they connect, rather than spherical. Establishing rounded edges and corners on a cube lends itself to easier manufacturing than the shot disclosed in U.S. Pat. No. 3,952,659.
Cubed shaped shot with sharp edges and corners (i.e., a radius approaching zero), that is properly stacked, has a packing density approaching the density of the shot material. As the edge and corner radius of curvature increases, the packing density decreases. When the radius of curvature equals half the cube width, the shot is spherical, and packing density is at a minimum. Cubic shot with no radius of curvature does not flow through metering devices used in automated loading very well (due to frequent bridging) and does not stack properly when charged into a shotshell cartridge. In fact, randomly loaded cubic shot with a small radius of curvature has a lower packing density and greater pattern dispersion than shot with a larger radius of curvature.
Preferred embodiments of shot in accordance with the principles of this invention achieve high packing density coupled with and superior ability to meter. One preferred embodiment of this invention provides a shot pellet for a shotshell that has a generally cubic shape comprising six generally square flat faces joined to adjacent faces by rounded edges having a radius of curvature of between about 15% and about 40%, and more preferably between about 25% and about 35%, of the distance between opposite faces of the generally cubic shaped pellet, with said radii being mostly tangentially rather than spherical. This tangential arrangement results from the radius of curvature not coinciding with the center of the shot. Non-tangential, spherical portions joining circular flat faces as in prior art, can result in pellets that do not meter as well as pellets with nearly tangential radius portions of this invention, due at least in part to sharp edges such as those shown in
Another preferred embodiment of this invention provides a shot pellet for a shotshell having a generally cubic shape comprising six generally square flat faces joined by rounded edges. The surface of the pellets is sufficiently smooth, and the edges being sufficiently rounded so that the pellets have a cylindrical packing density of at least 8% greater than the cylindrical packing density of spherical shot of the same weight.
The generally cubic shape of the shot of the preferred embodiment can provide more disruptive terminal performance on a target compared to rounder shot, such as conventional spherical pellets. Because of its greater packing density, the shot of the preferred embodiment can provide shotshell loadings at higher payloads or higher velocities.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
A shot pellet for a shotshell constructed according to the principles of this invention is indicated generally as 20 in
As seen in
The prior art shot pellet of U.S. Pat. No. 3,952,659 is shown in
The surface of the shot 20 is preferably smooth, which can contribute to better flight characteristics and distribution patterns when fired from a shotshell. The surface smoothness and rounded edges can make the shot flow and nest better, contributing to the increased packing density. The shot can be plated, for example with yellow zinc chromate, copper, nickel, zinc, chrome, or tin to enhance the smoothness and appearance of the shot.
The shot 20 can be made of any material typically used for ballistic spherical shot, such as lead, tin, tungsten, tungsten composites, copper, bismuth, iron (steel), or alloys/mixtures/composites thereof. The shot 20 is preferably made of steel or stainless steel. The shot can be made by cutting square wire into cubes and rounding the edges, for example by tumbling. Alternatively, the shot can be made by a heading operation between dies.
A 12 gauge shotshell according to another embodiment of this invention is indicated generally as 100 in
A wad 110 is disposed in the hull 104 behind the shot cup 108 separating the shot cup from propellant 112. A primer 114 in the head 102 is provided to ignite the propellant 112 when the shotshell 100 is fired.
The shotshell 100 can be of any size and have a wide variety of loads, but some preferred loads are 3½″ 12 gauge shell with a 1⅝ ounce load of BB sized shot and 3½ gauge shell with a 1⅜ ounce load of BB sized shot. The shotshell can be loaded for a variety of muzzle velocities, but is preferably load for 1400 fps muzzle velocity.
Table 1 compares the capacity and velocities of shells using embodiments of steel shot of the present invention, with the same sized spherical steel shot:
Table 1 shows that the steel shot of embodiments of the present invention allows shotshell loadings at increased payload/pellet count and/or greater velocity compared to loadings using conventional spherical shot.
In terms of performance, as indicated in Table 2, the steel shot embodiments of the present invention, when used with a unique shot cup (e.g., the shot cup disclosed in co-pending, co-assigned U.S. patent application Ser. No. 13/233,384, filed Sep. 15, 2011, and shown in U.S. Pat. No. D654137, the disclosure of which is incorporated herein by reference) achieve pattern densities (number of shot in a given area at a given distance) that exceed spherical shot. The performance will depend upon the choke and the construction of the shotshell, but Table 2 illustrates that embodiments of shot in accordance with the preferred embodiments of the present invention can result in more shot pellets hitting a given area, because more shot pellets can be loaded in the same volume.
Table 3 highlights how edge/corner radius affects various performance characteristics of cube pellets.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/453,315, filed Mar. 16, 2011, the entire disclosure of which is incorporated herein.
| Number | Date | Country | |
|---|---|---|---|
| 61453315 | Mar 2011 | US |
