Multi-caliber bolt assembly and method of using different sizes of ammunition in a firearm

Abstract

A multi-caliber bolt assembly includes a bolt body, a bolt face, an extractor, a case guide, and a resilient element. The extractor is movably coupled to the bolt body. The extractor is designed to engage and retain a rim of the cartridge casing. The case guide is movably coupled to the bolt body opposite the extractor. The case guide is designed to engage the cartridge casing. The resilient element is coupled to the extractor and the case guide. The resilient element is designed to exert a force to move the extractor and the case guide together to engage and hold the cartridge casing against the bolt face when the extractor and the case guide are moved apart against the force by insertion of the cartridge casing between the extractor and the case guide regardless of the size of the cartridge casing.

I claim: 
     
         1 . A multi-caliber bolt assembly comprising:
 a bolt body;   a bolt face, the bolt face being positioned at an end of the bolt body, the bolt face being configured to engage a cartridge casing for chambering;   an extractor, the extractor being movably coupled to the bolt body, the extractor being configured to engage and retain a rim of the cartridge casing;   a case guide, the case guide being movably coupled to the bolt body opposite the extractor, the case guide being configured to engage the cartridge casing together with the extractor; and   a resilient element, the resilient element being coupled to the extractor and the case guide, the resilient element being configured to exert a force to move the extractor and the case guide together to engage and hold the cartridge casing against the bolt face when the extractor and the case guide are moved apart against the force by insertion of the cartridge casing between the extractor and the case guide regardless of the size of the cartridge casing.   
     
     
         2 . The multi-caliber bolt assembly of  claim 1 , wherein:
 the extractor includes a first extractor end, a second extractor end, and a pivot pin positioned between the first extractor end and the second extractor end to pivotably mount the extractor on the bolt body;   the case guide includes a first case guide end, a second case guide end, and a pivot pin positioned between the first case guide end and the second case guide end to pivotably mount the case guide on the bolt body;   the resilient element is coupled to and between the second extractor end and the second case guide end;   the resilient element is configured to compress when the first extractor end and the first case guide are moved apart by the cartridge casing and the second extractor end and the second case guide end are thereby moved toward one another; and   the resilient element is configured to resiliently expand to exert the force to move the second extractor end and the second case guide end apart to thereby move the first extractor end and the first case guide end toward one another to engage and hold the cartridge casing.   
     
     
         3 . The multi-caliber bolt assembly of  claim 1 , wherein the resilient element is a spring. 
     
     
         4 . The multi-caliber bolt assembly of  claim 2 , wherein:
 the first extractor end includes a hook configured to be inserted into a case rim groove in the cartridge casing behind the rim of the cartridge casing to engage a front rim face of the rim to pull the cartridge casing out of a chamber of the firearm after firing; and   the first case guide end includes an outward protrusion configured to engage an outer rim edge of the rim of the cartridge casing to press the cartridge casing against the first extractor end.   
     
     
         5 . The multi-caliber bolt assembly of  claim 4 , wherein the hook and the outward protrusion are configured such that, during ejection of the cartridge casing from the firearm, the outer rim edge is pushed out of engagement with the outward protrusion and the cartridge casing is pivoted around the hook in engagement with the rear face of the rim and out of the firearm. 
     
     
         6 . The multi-caliber bolt assembly of  claim 4 , wherein each of the hook and the outward protrusion includes curved or beveled side surfaces for insertion of the cartridge casing in an upward direction perpendicular to a longitudinal axis of the cartridge casing. 
     
     
         7 . The multi-caliber bolt assembly of  claim 1 , wherein:
 the bolt body includes a pair of recessed slots opening in the bolt face;   each of the case guide and the extractor are positioned in a respective one of the recessed slots; and   each of the case guide and the extractor are configured to engage and be stopped by a slot surface of a respective one of the recessed slots when pivoted maximally toward one another.   
     
     
         8 . The multi-caliber bolt assembly of  claim 2 , wherein the resilient element is a spring. 
     
     
         9 . The multi-caliber bolt assembly of  claim 8 , wherein:
 the first extractor end includes a hook configured to be inserted into a case rim groove in the cartridge casing behind the rim of the cartridge casing to engage a front rim face of the rim to pull the cartridge casing out of a chamber of the firearm after firing; and   the first case guide end includes an outward protrusion configured to engage an outer rim edge of the rim of the cartridge casing to press the cartridge casing against the first extractor end.   
     
     
         10 . The multi-caliber bolt assembly of  claim 9 , wherein the hook and the outward protrusion are configured such that, during ejection of the cartridge casing from the firearm, the outer rim edge is pushed out of engagement with the outward protrusion and the cartridge casing is pivoted around the hook in engagement with the rear face of the rim and out of the firearm. 
     
     
         11 . The multi-caliber bolt assembly of  claim 10 , wherein each of the hook and the outward protrusion includes curved or beveled side surfaces for insertion of the cartridge casing in an upward direction perpendicular to a longitudinal axis of the cartridge casing. 
     
     
         12 . The multi-caliber bolt assembly of  claim 11 , wherein:
 the bolt body includes a pair of recessed slots opening in the bolt face;   each of the case guide and the extractor are positioned in a respective one of the recessed slots; and   each of the case guide and the extractor are configured to engage and be stopped by a slot surface of a respective one of the recessed slots when pivoted maximally toward one another.   
     
     
         13 . A method of using different sizes of ammunition in a firearm, the method comprising the steps of:
 providing a multi-caliber bolt assembly comprising:
 a bolt body; 
 a bolt face, the bolt face being positioned at an end of the bolt body, the bolt face being configured to engage a cartridge casing for chambering; 
 an extractor, the extractor being movably coupled to the bolt body, the extractor being configured to engage and retain a rim of the cartridge casing; 
 a case guide, the case guide being movably coupled to the bolt body opposite the extractor, the case guide being configured to engage the cartridge casing together with the extractor; and 
 a resilient element, the resilient element being coupled to the extractor and the case guide, the resilient element being configured to exert a force to move the extractor and the case guide together to engage and hold the cartridge casing against the bolt face when the extractor and the case guide are moved apart against the force by insertion of the cartridge casing between the extractor and the case guide regardless of the size of the cartridge casing; 
   loading a first cartridge casing of a first diameter in between the extractor and the case guide and thereby spacing the extractor and the case guide apart a first distance corresponding to the first diameter;   ejecting the first cartridge casing; and   loading a second cartridge casing of a second diameter different than the first diameter in between the extractor and the case guide and thereby spacing the extractor and the case guide apart a second distance corresponding to the second diameter, the second distance being different than the first distance.