High velocity, rimfire cartridge

Abstract

A .22 caliber rimfire cartridge includes a generally cylindrical casing having a rearward rimfire end and an opposing mouth end, wherein the rearward rimfire end has an annular rim connecting to a cylindrical casing portion extending to a casing forward edge and a bullet is disposed in the forward mouth end. In embodiments, the bullet comprises copper and a polymer binder. In embodiments, the bullet has a forward tapering portion with a central cavity, a first cylindrical portion with a first diameter and a cylindrical surface directly rearward of the tapering portion, a cylindrical driving band directly rearward of the first cylindrical portion, the cylindrical driving band having a second diameter greater than the first diameter and having an outer second cylindrical surface, a third cylindrical portion directly rearward of the cylindrical driving band, the third cylindrical portion having a third cylindrical surface with a diameter equal to the first diameter. In embodiments, the bullet is positioned with the third cylindrical surface mostly or entirely within the casing. In embodiments, the casing has a circumferential crimp positioned at the third circumferential portion. In embodiments, the third circumferential surface having a circumferential indentation at the circumferential crimp.

What is claimed is: 
     
         1 - 20 . (canceled) 
     
     
         21 . A .22 caliber rimfire cartridge comprising:
 a generally cylindrical casing comprising a rearward rimfire end and an opposing mouth end, wherein the rearward rimfire end comprises an annular rim connecting to a cylindrical casing portion extending to a casing forward edge of the mouth end;   a bullet disposed in the mouth end, the bullet comprising a first cylindrical portion comprising a first diameter and a cylindrical surface, a driving band directly rearward of the first cylindrical portion, the driving band comprising a second cylindrical surface with a second diameter greater than the first, a third cylindrical portion directly rearward of the cylindrical driving band, the third cylindrical portion comprising a third cylindrical surface with a diameter less than the second diameter,   wherein the bullet is positioned with the third cylindrical surface within the casing, the casing comprising a first circumferential crimp positioned at the third circumferential portion and rearward of the casing forward edge, the third circumferential surface comprising a first circumferential indentation at the first circumferential crimp.   
     
     
         22 . The rimfire cartridge of  claim 21 , wherein the bullet is lead-free, comprises copper and a polymer binder, and comprises a weight of from 19 to 23 grains. 
     
     
         23 . The rimfire cartridge of  claim 21 ,
 wherein the casing forward edge comprises a second circumferential crimp and the third circumferential surface comprises a second circumferential indentation at the second circumferential crimp and forward of the first circumferential crimp, and   wherein the second circumferential crimp comprises a rolled crimp at the mouth end.   
     
     
         24 . The rimfire cartridge of  claim 21 , wherein the bullet requires a pull force for separation from the casing of from 68 to 80 lbs. 
     
     
         25 . The rimfire cartridge of  claim 21 , the bullet further comprising a forward tapering portion with a central cavity, wherein the cylindrical surface of the first cylindrical portion is directly rearward of the forward tapering portion. 
     
     
         26 . The rimfire cartridge of  claim 25 , wherein the bullet comprises a hollow point. 
     
     
         27 . The rimfire cartridge of  claim 21 , wherein the driving band comprises a chamfer surface comprising a chamfer of 150 degrees±10 degrees, the angle measured between the chamfer surface and the first cylindrical surface. 
     
     
         28 . The rimfire cartridge of  claim 21 , wherein the driving band comprises a cylindrical surface with a diameter of 0.2240 inches±0.0010 inches, and an axial length of 0.050 inches±0.010 inches, and a length of 0.410 inches±0.020 inches, the driving band positioned forwardly of the mouth end. 
     
     
         29 . The rimfire cartridge of  claim 21 , wherein the bullet is positioned with the third portion at least 95% lengthwise within the casing. 
     
     
         30 . The rimfire cartridge of  claim 21 , wherein the second diameter of the driving band portion comprises a magnitude selected to provide a snug fit into a corresponding rifle bore when the cartridge is chambered in a match chambered rifle. 
     
     
         31 . The rimfire cartridge of  claim 21 , wherein the rimfire cartridge is dimensioned and configured so that the first cylindrical portion contacts rifling inside a rifle barrel when the cartridge is chambered in a match chambered rifle. 
     
     
         32 . The rimfire cartridge of  claim 21 , wherein the rimfire cartridge is dimensioned and configured so that the first cylindrical portion does not contact rifling inside a rifle barrel when the cartridge is chambered in a sporting chambered rifle. 
     
     
         33 . The rimfire cartridge of  claim 21 , wherein the second diameter of the driving band portion comprises a magnitude selected so that the driving band portion engages rifling inside a rifle barrel after the cartridge is chambered in a sporting chambered rifle and the rifle is fired, igniting cartridge propellant. 
     
     
         34 . The rimfire cartridge of  claim 21 , further comprising a slow burning propellant and a primer material disposed inside the casing, the slow burning propellant comprising a first weight and a first volume, the primer comprising a second weight and a second volume, wherein one or more of:
 a weight ratio of the first weight to the second weight is less than 100, and   a volume ratio of the first volume to the second volume is less than 100.   
     
     
         35 . The rimfire cartridge of  claim 21 , wherein the driving band is dimensioned and configured to engage rifling inside a rifle barrel after the cartridge is chambered in a rifle and the rifle is fired igniting cartridge propellant and the first cylindrical portion is dimensioned and configured to travel forwardly along the rifling inside rifle barrel after the cartridge is chambered in a rifle and the rifle is fired igniting cartridge propellant. 
     
     
         36 . A rimfire cartridge comprising:
 a generally cylindrical casing comprising a rearward rimfire end and an opposing mouth end, wherein the rearward rimfire end comprises an annular rim connecting to a cylindrical casing portion extending to a casing forward edge of the mouth end;   a bullet disposed in the mouth end, the bullet comprising a forward tapering portion, a forward cylindrical portion comprising a first diameter and a cylindrical surface directly rearward of the forward tapering portion, a rearward portion rearward of the forward portion,   wherein the bullet is positioned with the rearward portion within the casing, the casing comprising a circumferential crimp positioned at the rearward portion rearward of the casing forward edge, the rearward surface comprising a circumferential indentation at the circumferential crimp.   
     
     
         37 . The rimfire cartridge of  claim 36 , the bullet further comprising copper and a polymer binder, and the forward tapering portion of the bullet comprises a central cavity,
 wherein the crimp is configured such that the cartridge requires a pull force for separation from the casing of greater than 70 lbs.   
     
     
         38 . The rimfire cartridge of  claim 36 , the bullet further comprising:
 the rearward portion comprising a rearward surface with a diameter equal to or less than the first diameter, and   a driving band rearward of the first cylindrical portion and forward of the rearward portion, the driving band comprising a second cylindrical surface with a second diameter greater than the first, and   wherein the casing forward edge comprises a forward circumferential crimp.   
     
     
         39 . The rimfire cartridge of  claim 38 , wherein the bullet comprises a core and a jacket, the jacket at least partially surrounding the core,
 wherein the core composition is selected from zinc, tin, lead, copper powder, and iron powder, and   wherein the jacket composition is selected from copper, brass plated steel, brass, plated steel, and a polymer.   
     
     
         40 . A rimfire cartridge comprising:
 a generally cylindrical casing comprising a rearward rimfire end and an opposing mouth end, wherein the rearward rimfire end comprises an annular rim and the mouth end comprises a casing forward edge;   a bullet disposed in the mouth end, the bullet comprising a forward cylindrical portion comprising a forward surface, a rearward cylindrical portion rearward of the forward portion, the rearward cylindrical portion comprising a rearward surface, wherein the bullet is positioned with the rearward surface within the casing,   the casing forward edge comprising a first circumferential crimp, and   the casing comprising a second circumferential crimp positioned at the rearward cylindrical portion rearward of the casing forward edge, the third surface comprising a circumferential indentation at the second circumferential crimp.