Method and apparatus for cartridge identification imprinting in difficult contexts by recess protected indicia

Abstract

Imprinting an identification indicia on a cartridge in a difficult context, such as on a coated cartridge or on a high power cartridge. A marking indicia is formed on a base surface located in the interior surface of a cartridge chamber containing the cartridge and includes marking lands raised with respect to the base surface and a maximum marking indicia elevation above the base surface that is coplanar with the interior surface. The marking indicia is thereby recessed with respect to the interior surface and the identification indicia is thereby recessed with respect to the imprint surface.

1 . A marking indicia located on an interior surface of a firearm chamber to imprint an identification indicia on an imprint surface of a cartridge when the cartridge is fired, comprising: 
 a base surface located in the interior surface of a chamber containing the cartridge,    a plurality of marking lands raised with respect to the base surface and with a maximum marking indicia elevation above the base surface that is coplanar with the interior surface, and    a plurality of marking floors between and separating the marking lands, wherein 
 when the cartridge is fired the marking indicia and the imprint surface are forced into mutual contact to imprint a reverse image of the marking indicia in the imprint surface as the identification surface, and wherein  
   the identification indicia includes 
 a plurality of indicia lands corresponding to the marking floors, and  
 a plurality of indicia floors corresponding to the marking lands, wherein 
 the indicia lands are elevated with respect to the indicia floors with a maximum identification indicia elevation above the indicia floors that is coplanar with the imprint surface, so that  
 
   the marking indicia is recessed with respect to the interior surface, and    the identification indicia is recessed with respect to the imprint surface.    
   
   
       2 . The marking indicia of  claim 1  wherein: 
 the interior surface is a striking surface of a firing pin and the marking indicia is brought into contact with the imprint surface by a striking action of the firing pin against the imprint surface, and    the imprint surface is located on a primer of the cartridge.    
   
   
       3 . The marking indicia of  claim 1  wherein: 
 the interior surface is an inner surface of the firearm chamber abutting a wall of the cartridge case, and    the marking indicia is brought into contact with the imprint surface by expansion of the cartridge case wall due to a propellant charge pressure in the cartridge case.    
   
   
       4 . The marking indicia of  claim 1  wherein: 
 a maximum width of the marking indicia is less than 200 microns, and    a maximum width of a marking land is less than 35 microns.    
   
   
       5 . The marking indicia of  claim 1  wherein: 
 the marking indicia is a holographic image.    
   
   
       6 . The marking indicia of  claim 1 , wherein: 
 an angle of each interior wall extending between a point on a marking land and an adjacent point of a marking floor is in the range of 6 to 22.5 degrees.    
   
   
       7 . The marking indicia of  claim 1 , wherein: 
 a ratio between an area of the marking lands of a marking indicia and the total area of the marking indicia is in the range of 6:1 to greater than 9:1.    
   
   
       8 . A method for imprinting an identification indicia on an imprint surface of a cartridge when the cartridge is fired, comprising: 
 forming a marking indicia on a base surface located in the interior surface of a chamber containing the cartridge,    the marking indicia including 
 a plurality of marking lands raised with respect to the base surface and with a maximum marking indicia elevation above the base surface that is coplanar with the interior surface, and  
 a plurality of marking floors between and separating the marking lands, and  
 when the cartridge is fired, forcing the marking indicia and the imprint surface into mutual contact to imprint a reverse image of the marking indicia in the imprint surface as the identification surface, wherein  
   the identification indicia includes 
 a plurality of indicia lands corresponding to the marking floors, and  
 a plurality of indicia floors corresponding to the marking lands, wherein  
 the indicia lands are elevated with respect to the indicia floors with a maximum identification indicia elevation above the indicia floors that is coplanar with the imprint surface, so that  
   the marking indicia is recessed with respect to the interior surface, and    the identification indicia is recessed with respect to the imprint surface.    
   
   
       9 . The method of  claim 8  for imprinting an identification indicia on an imprint surface of a cartridge when the cartridge is fired, wherein: 
 the interior surface is a striking surface of a firing pin and the marking indicia is brought into contact with the imprint surface by a striking action of the firing pin against the imprint surface, and    the imprint surface is located on a primer of the cartridge.    
   
   
       10 . The method of  claim 8  for imprinting an identification indicia on an imprint surface of a cartridge when the cartridge is fired, wherein: 
 the interior surface is an inner surface of the firearm chamber abutting a wall of the cartridge case, and    the marking indicia is brought into contact with the imprint surface by expansion of the cartridge case wall due to a propellant charge pressure in the cartridge case.    
   
   
       11 . The method of  claim 8  for imprinting an identification indicia on an imprint surface of a cartridge when the cartridge is fired, wherein: 
 a maximum width of the marking indicia is less than 200 microns, and    a maximum width of a marking land is less than 35 microns.    
   
   
       12 . The method of  claim 8  for imprinting an identification indicia on an imprint surface of a cartridge when the cartridge is fired, wherein: 
 the marking indicia is a holographic image.    
   
   
       13 . The method of  claim 8  for imprinting an identification indicia on an imprint surface of a cartridge when the cartridge is fired, wherein: 
 an angle of each interior wall extending between a point on a marking land and an adjacent point of a marking floor is in the range of 6 to 22.5 degrees.    
   
   
       14 . The method of  claim 8  for imprinting an identification indicia on an imprint surface of a cartridge when the cartridge is fired, wherein: 
 a ratio between an area of the marking lands of a marking indicia and the total area of the marking indicia is in the range of 6:1 to greater than 9:1.