Small arms cartridge

Inactive Publication Date: 2020-04-30
LIGHTFORCE USA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent text explains that the new cartridge has a sharper shoulder angle of 40 degrees, which allows for longer case life and reduced material flow during peak pressures. This design prevents the brass case from flowing forward and results in stronger necks and shoulder junctions. Additionally, the cartridge has been found to be reloadable at least four times without annealing or trimming. The expectation is that it can be reloaded at least eight times, with necessary annealing and trimming procedures, without diminished performance.

Problems solved by technology

With traditional 20°-30° shoulder angles, internal pressures cause the brass case to “flow” forward, resulting in thin necks and shoulder junctions.
Thin spots eventually result in cracked cases that are no longer usable for reloading.
With large cases, over-pressuring often results in the inability to extract fired brass from the chamber.
The cartridge does not perform according to internal / external ballistic calculation predictions for the amount of propellant and weight / BC of the projectile.

Method used

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  • Small arms cartridge
  • Small arms cartridge
  • Small arms cartridge

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0029]A Flat Line™ .375 caliber bullet made by Warner Tool Company of North Swanzey, N.H., provides a 361 grain, solid copper bullet having a 2.20 inch overall length (OAL). This projectile includes a 16° boat tail and may be made in accordance with the invention described in U.S. Patent Application Publication No. 2016 / 0327380, published Nov. 10, 2016, the contents of which are hereby incorporated herein by reference. This projectile has ballistic coefficients (BC) acoustically measured in the range of 3,000 to 15,000 fps of G1BC=0.980 and G7BC=0.494. Ballistic coefficients measured by Doppler radar chronograph of G1BC=0.961 and G7BC=0.480. The minimum twist recommended for this projectile is 1:10 inches. The inventors have found a preferred twist rate of 1:8.65 inches to 1:8.75 inches. This example is illustrated in FIG. 4.

example 2

[0030]A non-standard 400 grain, .375 caliber, solid copper bullet made by Berger Bullets LLC of Fullerton, Calif. Sample projectiles have a calculated BC greater than 1.0 (about 1.1). Warner Tool Company, referenced above, also makes a 400 grain, .375 caliber projectile that is suitable.

example 3

[0031]A MTAC™ (match / tactical) 3.745 / .3655 caliber, 402 grain, solid copper projectile made by Cutting Edge Machining Solutions Inc., d / b / a Cutting Edge Bullets, of Drifting, Pa., having a G1BC=0.990 and OAL of 2.209 inches. This projectile requires a twist of 1:7.5 inches or faster.

[0032]A primer (well-known, not shown) sized to seat in a primer pocket 22 configured for .50 BMG-size primers may be used. The geometry of the case 12 of the present invention provides maximum performance using a medium-slow burning powder, generally in the category of those designed for the .338 Lapua Magnum or .50 BMG cartridges. H50BMG or similar powders may be used. A powder designed for the .338 Lapua Magnum cartridge having a burn rate only slightly faster than powder intended for .50 BMG cartridge may provide better performance. For example, 168 grains of Reloder® 33 propellant powder by Alliant Powder of Anoka, Minn., has been used in the cartridge 10 of the present invention to propel a 361 gra...

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Abstract

Provided is a centerfire rifle cartridge. A case has a head end, an open mouth end for receiving a projectile, and a central axis. The head end has a base portion substantially conforming to that of a .50 BMG cartridge. The case has a case wall with a taper of up to 1.0° relative to the central axis. A frusto-conical shoulder portion extends from the case wall and has an angle of approximately 40° relative to the central axis. A neck portion extends from the shoulder portion and has a mouth sized to receive a .375 caliber (9.5 mm) projectile.

Description

RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Patent Application No. 62 / 580,476, filed Nov. 2, 2017, and incorporates the same herein by reference.TECHNICAL FIELD[0002]This invention relates to a firearm cartridge and barrel chamber for it. More particularly, it relates to a cartridge and cartridge load combination for efficient, high-velocity, long-range, precision shooting.BACKGROUND[0003]Ballistics, the science and study of projectiles and firearms, may be divided into three categories. These are: interior ballistics, exterior ballistics, and terminal ballistics. Interior ballistics relates to the propulsion of a projectile, through the bore of a barrel, to achieve a determined velocity as it leaves the muzzle of the barrel. Exterior ballistics relates to the flight of the projectile and how that flight is affected by its shape, its velocity, and external forces, including wind and gravity. Terminal ballistics relates to what effect the projectile...

Claims

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Application Information

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IPC IPC(8): F42B5/26F42B5/02F42B10/38
CPCF42B5/025F42B10/38F42B5/26F42B5/02
InventorSUMMERFIELD, ABRAM W.BOYD, PIETROWISDOM, KRISTOFERDENNIS, RAYMOND L.
OwnerLIGHTFORCE USA