Rimfire type firearms having centerfire firearm components and related methods

Abstract

Firearms include some components originally configured for use with centerfire cartridge ammunition, such as a lower portion, and other components configured for use with rimfire cartridges, such as an upper portion and magazine. The firearm is thus configured for firing rimfire cartridge ammunition, although some components of the firearm may be characterized as centerfire firearm components. Methods of fabricating firearms involve assembly of a rimfire upper portion with a centerfire lower portion. A magazine is provided that is configured to couple to the centerfire lower portion, and to feed rimfire cartridges from within the magazine into the rimfire upper portion. Methods of adapting a centerfire firearm for use with rimfire cartridges involve removal of a centerfire barrel and upper portion from a centerfire lower portion, and attachment of a second upper portion and a second barrel, each configured for use with rimfire cartridge ammunition, to the centerfire lower portion.

What is claimed is: 
     
         1 . A firearm, comprising:
 a stock;   a receiver assembly attached to the stock, the receiver assembly including a lower portion and an upper portion;   a barrel extending from the receiver assembly;   a firing chamber located at the proximal end of the barrel; and   a magazine configured for holding a plurality of unfired rimfire cartridges therein, the magazine configured to be repeatedly coupled to and decoupled from the receiver assembly;   wherein the upper portion comprises an action mechanism configured to move an unfired rimfire cartridge from the magazine into the firing chamber, and to remove the rimfire cartridge from the firing chamber and to eject the rimfire cartridge from the receiver assembly, the action mechanism including a bolt disposed proximal to the firing chamber and movable between an open position and a closed position, the upper portion further comprising a firing pin configured to strike a rim of a rimfire cartridge in the firing chamber upon actuation of a trigger;   wherein the lower portion comprises a trigger mechanism configured to cause movement of the firing pin upon actuation of a trigger of the trigger mechanism, the lower portion further comprising a housing defining a receptacle configured to receive the magazine therein; and   wherein the lower portion of the receiver assembly is sized and configured for use with another upper portion and another magazine, the another upper portion and another magazine configured for use with centerfire cartridges.   
     
     
         2 . The firearm of  claim 1 , wherein the magazine has an external length, width, and height, and wherein the magazine is not capable of receiving cartridges therein having a length greater than about 75% of the external length of the magazine. 
     
     
         3 . The firearm of  claim 2 , wherein the magazine is not capable of receiving cartridges therein having a length greater than about 50% of the external length of the magazine. 
     
     
         4 . The firearm of  claim 3 , wherein the magazine is not capable of receiving cartridges therein having a length greater than about 40% of the external length of the magazine. 
     
     
         5 . The firearm of  claim 4 , wherein the magazine is not capable of receiving cartridges therein having a length greater than about 35% of the external length of the magazine. 
     
     
         6 . The firearm of  claim 1 , wherein the firearm has a headspace of 0.075″ or less. 
     
     
         7 . The firearm of  claim 1 , wherein the firing chamber is sized and configured to fire one of .17 HORNADY MACH 2 cartridges, .17 HORNADY MAGNUM RIMFIRE cartridges, 5 mm REMINGTON RIMFIRE MAGNUM cartridges, .22 long rifle rimfire cartridges, and .22 WINCHESTER MAGNUM RIMFIRE cartridges. 
     
     
         8 . A method of manufacturing a firearm, comprising:
 providing a barrel configured for used with rimfire cartridges;   forming an upper portion configured for use with rimfire cartridges, the upper portion comprising an action mechanism configured to move an unfired rimfire cartridge from a magazine into a firing chamber at least partially defined in a proximal end of the barrel, and to remove the rimfire cartridge from the firing chamber and to eject the rimfire cartridge from the receiver assembly, the action mechanism including a bolt disposed proximal to the firing chamber and movable between an open position and a closed position, the upper portion further comprising a firing pin configured to strike a rim of a rimfire cartridge in the firing chamber upon actuation of a trigger;   attaching the upper portion and the barrel to a lower portion and a stock sized and configured for use with another upper portion and another barrel each configured for use with centerfire cartridges, the lower portion comprising at least a portion of a trigger mechanism configured to cause movement of the firing pin upon actuation of a trigger of the trigger mechanism, the lower portion further comprising a housing defining a receptacle configured to receive a magazine therein; and   providing a magazine configured for holding a plurality of unfired rimfire cartridges therein, the magazine configured to be repeatedly coupled to and decoupled from the upper portion and lower portion.   
     
     
         9 . The method of  claim 8 , further comprising forming the magazine. 
     
     
         10 . The method of  claim 9 , wherein forming the magazine comprises forming the magazine to have an external length, width, and height, and configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 75% of the external length of the magazine. 
     
     
         11 . The method of  claim 10 , further comprising configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 50% of the external length of the magazine. 
     
     
         12 . The method of  claim 11 , further comprising configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 40% of the external length of the magazine. 
     
     
         13 . The method of  claim 12 , further comprising configuring the magazine such that the magazine is not capable of receiving cartridges therein having a length greater than about 35% of the external length of the magazine. 
     
     
         14 . The method of  claim 8 , further comprising configuring the upper portion such that the firearm has a headspace of 0.075″ or less. 
     
     
         15 . The method of  claim 8 , further comprising selecting the barrel and configuring each of the upper portion and magazine for use with one of .17 HORNADY MACH 2 cartridges, .17 HORNADY MAGNUM RIMFIRE cartridges, 5 mm REMINGTON RIMFIRE MAGNUM cartridges, .22 long rifle rimfire cartridges, and .22 WINCHESTER MAGNUM RIMFIRE cartridges. 
     
     
         16 . The method of  claim 15 , further comprising selecting the stock and the lower portion to comprise a stock and a lower portion of a firearm configured to fire .308 WINCHESTER centerfire cartridges. 
     
     
         17 . A method of using a firearm, comprising:
 selecting a firearm configured to fire centerfire cartridges;   removing a first barrel and a first upper portion of a first receiver assembly from the firearm;   providing a second barrel and a second upper portion configured for use with rimfire cartridges, the second upper portion comprising an action mechanism configured to move an unfired rimfire cartridge from a magazine into a firing chamber at least partially defined in a proximal end of the second barrel, and to remove the rimfire cartridge from the firing chamber and to eject the rimfire cartridge from the upper portion, the action mechanism including a bolt disposed proximal to the firing chamber and movable between an open position and a closed position, the second upper portion further comprising a firing pin configured to strike a rim of a rimfire cartridge in the firing chamber upon actuation of a trigger;   attaching the second upper portion and the second barrel to a lower portion and a stock of the firearm, the lower portion comprising at least a portion of a trigger mechanism configured to cause movement of the firing pin upon actuation of a trigger of the trigger mechanism, the lower portion further comprising a housing defining a receptacle configured to receive a magazine therein; and   providing a magazine configured for holding a plurality of unfired rimfire cartridges therein, the magazine configured to be repeatedly coupled to and decoupled from the second upper portion and the lower portion.   
     
     
         18 . The method of  claim 17 , further comprising selecting the magazine to have an external length and width, the magazine not being capable of receiving cartridges therein having a length greater than about 75% of the external length of the magazine. 
     
     
         19 . The method of  claim 18 , wherein the magazine is not capable of receiving cartridges therein having a length greater than about 50% of the external length of the magazine. 
     
     
         20 . The method of  claim 19 , wherein the magazine is not capable of receiving cartridges therein having a length greater than about 35% of the external length of the magazine. 
     
     
         21 . The method of  claim 17 , further comprising selecting the second barrel, the second upper portion, and the magazine for use with one of .17 HORNADY MACH 2 cartridges, .17 HORNADY MAGNUM RIMFIRE cartridges, 5 mm REMINGTON RIMFIRE MAGNUM cartridges, .22 long rifle rimfire cartridges, and .22 WINCHESTER MAGNUM RIMFIRE cartridges. 
     
     
         22 . The method of  claim 21 , wherein selecting the firearm comprises selecting a firearm configured for firing .308 WINCHESTER centerfire cartridges.