Gun barrel rifling
The present invention relates to polygonal rifling of a gun barrel to provide grooves and bores in the gun barrel separated by a flat area which tapers from the bore to the groove. There is an angle from the center of the bore to the corner of the flat area, that is, where the flat area meets the bore. The angle is predetermined by the bore dimensions.
This application hereby claims the benefit under 35 U.S.C. §119(e) of Provisional Application Ser. No. 61/433,374, filed Jan. 17, 2011, entitled GUN BARREL RIFLING, which application is incorporated herein by reference in its entirety.
FIELD OF INVENTIONThe present invention relates to rifling of gun barrels. More specifically, the present invention relates to rifling of gun barrels to provide a polygonal cross-sectional configuration. The invention provides for more accurate travel of a bullet, including solid copper, copper-jacketed steel core and copper-jacketed soft-core bullets.
BACKGROUND OF THE INVENTIONRifling of gun barrels is well known in the art. Gun barrels are rifled using three known techniques namely cut rifling, button rifling and hammer forge rifling. The cross-section of the rifling may generally be described as conventional rifling providing for a cross-sectional gear shaped configuration or polygonal rifling providing for a polygonal configuration. The present invention relates to polygonal rifling.
The prior art discloses polygonal rifling such as disclosed in U.S. Pat. No. 3,643,364 (“the '364 patent”) directed to a rifled gun barrel with the interior cross-sectional configuration defining a regular curvilinear polygon. The disclosure of the '364 patent is incorporated in its entirety herein by reference. The '364 patent discloses a three arc radius providing for a polygonal shape having a blended radius 4 from the groove 5 to the flattened portion 3 to adjacent groove 5. A problem with this configuration is in the blended radius. When the bullet rotates on its helix angle as it passes through the barrel, the bullet jacket will be deformed and become non-symmetrical. This causes the center of gravity of the bullet to move off center and the bullet may not travel as straight as a bullet with a center of gravity more on center.
The prior art rifling while useful has various shortcomings and improvement to barrel rifling is desirable to provide for more accurate tracking of bullets. The rifling techniques of the present invention provide such improvement.
SUMMARY OF INVENTIONA primary object of the present invention is to provide an improved polygonal rifling for a gun barrel. The invention allows the bullet to fly straighter and track more accurately.
The rifling of the present invention precludes any substantial deformation of the bullet jacket with minimal engraving and in particular in copper jacket bullets. The rifling, therefore, allows the bullet to move more symmetrically along the barrel and, therefore, the bullet will track more accurately to the target.
The rifling of the present invention provides additional improvement over the prior art as it includes no sharp corners of the lands. In this application, the area between the grooves will be referred to as the “bore” area or “bores,” which area is also sometimes referred to in the art as the “lands.”
The rifling of the present invention generally provides a tight seal around the bullet when the bullet enters the rifling in the barrel and has no sharp corners which will deform the bullet jacket and change the center of gravity of the bullet.
The present invention is, therefore, directed to a gun barrel having polygonal rifling comprising helically disposed rifling grooves in a barrel bore and having a flat area between the grooves and the bore. The flat area includes corner areas. The groove diameter is greater than the bore diameter and the flat area dimensions which connects the groove diameter and the bore diameter is less than the bore diameter.
These primary and other objects of the invention will be apparent from the following description of the preferred embodiments of the invention and from the accompanying drawings.
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The polygonal rifling of the present invention may be made by known rifling techniques including cut rifling, button rifling and hammer forge rifling.
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With the rifling of the present invention, the bullet gets pushed into the rifling at the throat of the chamber and centers up in the bore. As the bullet is pushed through the barrel at high velocities, with a right hand twist the left side will have a wind up effect and the stress at that corner where the groove meets the bore will not deform the bullet due to the corners of the flat area between the bore and groove. This is different from the polygonal rifling of the '364 patent wherein the bullet may rotate somewhat when placed in the bore due to the blended radius. When the bullet is fired from the rifle using the rifling of the present invention, the bullet follows the helix angle, e.g. twist rate of the rifling, and the stress from the wind up effect of the bullet on the corners of the polygonal shape creates no or little bullet deformation and provides for more accurate tracking of the bullet when leaving the barrel.
The exemplary embodiments herein disclosed are not intended to be exhaustive or to unnecessarily limit the scope of the invention. The exemplary embodiments were chosen and described in order to explain the principles of the present invention so that others skilled in the art may practice the invention. As will be apparent to one skilled in the art, various modifications can be made within the scope of the aforesaid description. Such modifications being within the ability of one skilled in the art form a part of the present invention and are embraced by the appended claims.
Claims
1. A gun barrel having polygonal rifling comprising helically disposed rifling grooves in a barrel bore and having a flat area between said grooves and said bore, said flat area including corner areas, wherein the groove diameter is greater than the bore diameter and the flat area dimensions which connects the groove diameter and the bore diameter is less than the bore diameter.
2. A gun barrel according to claim 1 wherein there are six grooves and six bores.
3. A gun barrel according to claim 2 wherein the groove diameter is about 0.224 inches, the bore diameter is about 0.219 inches and the flat diameter is about 0.215 inches.
4. A gun barrel according to claim 3 wherein an angle from the center of the bore area to the corner of the flat area is about 4.7 degrees.
5. A gun barrel according to claim 1 wherein the rifling provides a twist in the rifled barrel which is substantially uniform from the breech end of the barrel to the muzzle end of the barrel.
6. A gun barrel according to claim 1 wherein a bullet fired through the barrel will not have any substantial deformation due to the corners of the flat area between the bore and groove.
7. A gun barrel according to claim 1 wherein a bullet fired through the barrel follows the helix angle of the rifling and the stress from the wind up effect of the bullet of the corners of the polygonal shape creates substantially no or little bullet deformation.
Type: Application
Filed: Jan 17, 2012
Publication Date: Jul 19, 2012
Inventor: Frederick J. Feddersen (Knoxville, TN)
Application Number: 13/374,820