Rifling profile for firearms

Abstract

A firearm barrel is provided having a body defining an outer surface and a bore. The bore may define a rifling profile along at least a portion of a length of the barrel. The rifling profile may define a cross-sectional profile perpendicular to the length of the barrel at a location along the length of the barrel. The cross-sectional profile may include a plurality of arcuate portions and a plurality of linear portions. The cross-sectional profile may define a cross-sectional area defined by a Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) standard rifling profile. Various embodiments may include firearms, assemblies, components, and methods associated with such firearms and firearm barrels.

1 - 20 . (canceled) 
     
     
         21 . A firearm barrel defining a center axis and configured to receive a bullet having a caliber, the firearm barrel comprising:
 a body defining an outer surface and a bore,   wherein:
 the bore defines a rifling profile along at least a portion of a length of the firearm barrel, 
 the rifling profile defines a cross-sectional profile perpendicular to the length of the firearm barrel at a location along the length of the firearm barrel, and 
 the cross-sectional profile comprises a plurality of arcuate portions and a plurality of linear portions. 
   
     
     
         22 . The firearm barrel of  claim 21 , wherein:
 the firearm barrel is configured to receive a 6.5 mm bullet having a caliber that is equal to 0.264 inch,   the plurality of linear portions each define a first radius at their closest point to the center axis at the location and the plurality of arcuate portions each define a second radius to the center axis at the location, and   the second radius is at least 0.1315 inch and up to 0.132 inch.   
     
     
         23 . The firearm barrel of  claim 22 , wherein the plurality of arcuate portions and the plurality of linear portions consist of six arcuate portions and six linear portions. 
     
     
         24 . The firearm barrel of  claim 23 , wherein the cross-sectional profile defines a cross-sectional area that is compliant with a Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) standard rifling profile for the 6.5 mm bullet such that the cross-sectional area is at least 0.0536 square inches. 
     
     
         25 . The firearm barrel of  claim 24 , wherein the first radius is 96.7% to 97.5% of the second radius. 
     
     
         26 . The firearm barrel of  claim 21 , wherein the plurality of linear portions each define a first radius at their closest point to the center axis at the location and the plurality of arcuate portions each define a second radius to the center axis at the location, and wherein the first radius is 97.5% to 97.8% of the second radius. 
     
     
         27 . The firearm barrel of  claim 21 , wherein at least a portion of the bore, including a first portion of the bore at the location, is coated with a coating, wherein the coating comprises chrome. 
     
     
         28 . The firearm barrel of  claim 21 , wherein the plurality of arcuate portions and the plurality of linear portions comprise alternating arcuate portions and linear portions. 
     
     
         29 . The firearm barrel of  claim 21 , wherein a diameter of the bore spanning two opposite arcuate portions of the plurality of arcuate portions is approximately equal to the caliber of the bullet that the firearm barrel is configured to receive. 
     
     
         30 . The firearm barrel of  claim 21 , wherein the rifling profile comprises an even number of the plurality of linear portions and an even number of the plurality of arcuate portions. 
     
     
         31 . The firearm barrel of  claim 21 , wherein the plurality of linear portions define a first diameter at their closest point to the center axis at the location and the plurality of arcuate portions define a second diameter to the center axis at the location, wherein the firearm barrel is configured to receive a 0.277 Fury or 6.8 mm caliber bullet, wherein the first diameter is 0.270 and the second diameter is 0.277. 
     
     
         32 . The firearm barrel of  claim 21 , wherein the firearm barrel is configured to receive a M855 or M193 bullet. 
     
     
         33 . The firearm barrel of  claim 21 , wherein the cross-sectional profile defines a cross-sectional area that is at least 0.0388 square inch in an instance in which the firearm barrel is configured to receive a 0.223 caliber bullet. 
     
     
         34 . The firearm barrel of  claim 21 , wherein the cross-sectional profile comprises at least three and up to five arcuate portions and at least three and up to five linear portions. 
     
     
         35 . The firearm barrel of  claim 21 , wherein the bullet that the firearm barrel is configured to receive is a bullet from a high pressure cartridge. 
     
     
         36 . A firearm comprising:
 a receiver;   a trigger assembly;   a buttstock; and   a barrel defining a center axis and configured to receive a bullet having a caliber, the barrel comprising:
 a body defining an outer surface and a bore, 
 wherein: 
 the bore defines a rifling profile along at least a portion of a length of the barrel, 
 the rifling profile defines a cross-sectional profile perpendicular to the length of the barrel at a location along the length of the barrel, and 
 the cross-sectional profile comprises a plurality of arcuate portions and a plurality of linear portions. 
   
     
     
         37 . The firearm of  claim 36 , wherein:
 the barrel is configured to receive a 6.5 mm bullet having a caliber that is equal to 0.264 inch,   the plurality of linear portions each define a first radius at their closest point to the center axis at the location and the plurality of arcuate portions each define a second radius to the center axis at the location,   the second radius is at least 0.1315 inch and up to 0.132 inch,   the first radius is 96.7% to 97.5% of the second radius,   the plurality of arcuate portions and the plurality of linear portions consist of six arcuate portions and six linear portions, and   the cross-sectional profile defines a cross-sectional area that is compliant with a Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) standard rifling profile for the 6.5 mm bullet such that the cross-sectional area is at least 0.0536 square inches.   
     
     
         38 . The firearm of  claim 36 , wherein the plurality of linear portions each define a first radius at their closest point to the center axis at the location and the plurality of arcuate portions each define a second radius to the center axis at the location, and wherein the first radius is 97.5% to 97.8% of the second radius. 
     
     
         39 . A method of manufacturing a firearm barrel, the method comprising:
 removing material from a piece of metal to define a cross-sectional profile perpendicular to a length of the piece of metal at a location along the length of the piece of metal,   wherein the cross-sectional profile comprises a plurality of arcuate portions and a plurality of linear portions.   
     
     
         40 . The method of  claim 39 , wherein the plurality of linear portions each define a first radius at their closest point to a center axis at the location and the plurality of arcuate portions each define a second radius to the center axis at the location, and wherein the first radius is 97.5% to 97.8% of the second radius.