Conversion breech plug for muzzleloading rifles to receive shotgun primers and method of using the same

Abstract

A breech plug for a muzzleloading rifle has an elongated body with external threads and having rearward and forward ends. A circular depression is formed in the rearward end of the body and is surrounded by an annular rim. The annular rim has an inner diameter slightly less than the diameter of a bore of the barrel of the rifle. The depression has a tapered bottom surface that slopes inwardly and rearwardly and terminates in a first center bore extending longitudinally along a center axis of the body. A narrow diameter bore connects the first center bore with a second bore having a diameter substantially the same as the first center bore. The second center bore terminates in an enlarged bore portion adapted to receive a propellant material. The first center bore provides an expansion chamber for a large percussion element to be ignited in the depression. The narrow diameter bore allows the products of combustion from the first center bore to enter the second center bore, but prevents blowback in a reverse direction from the combustion of powder downstream from the second bore. The depression has a diameter substantially twice the diameter of the first center bore.

What is claimed is:  
     
         1 . A breech plug for a muzzleloading rifle comprising: 
 an elongated body with external threads and having rearward and forward ends,    a circular depression in the rearward end of the body surrounded by an annular rim,    the annular rim having an inner diameter slightly less than the diameter of the bore of the barrel,    the depression having a tapered bottom surface that slopes inwardly and rearwardly and terminating in a first center bore extending longitudinally along a center axis of the body,    a narrow diameter bore connecting the first center bore with a second center bore having a diameter substantially the same on the first center bore,    the second center bore terminating in a chamber portion,    the second center bore providing an expansion chamber for a percussion element ignited in the chamber portion adjacent the second center bore, and    the narrow diameter bore allowing products of combustion from the second center bore to enter the first center bore, but preventing blowback in a reverse direction from the explosion of powder within the first center bore.    
     
     
         2 . The breech plug of  claim 1  wherein enlarged bore portion has tapered side walls.  
     
     
         3 . The breech plug of  claim 1  wherein the depression has a diameter substantially twice that of the diameter of the second center bore.  
     
     
         4 . A method of converting a conventional muzzleloading rifle having a breech plug threadably inserted into the rearward end of a rifle barrel, and having a rearward end fitted only to receive a rifle primer, or ignition by a striking pin, comprising 
 removing the striking pin and the breech plug from the rifle,    replacing the removed breech plug with a conversion breech plug having threads identical to those of the removed breech plug and having a rearward end capable of receiving a shotgun primer,    using a striker pin capable of igniting the shotgun primer when the striker pin is actuated,    providing an expansion chamber immediately forwardly of the shotgun primer,    placing a narrow diameter restricter passageway forwardly of the expansion chamber,    placing a second elongated chamber having a diameter substantially the same as the diameter of the expansion chamber immediately forward of the small diameter conduit,    and placing a propellant material in a forward end of the second center bore,    whereby the ignition of the propellant will take place by igniting the shotgun primer wherein the products of combustion will move through the narrow diameter restricter passageway and thence into the second center bore to ignite the propellant material,    whereby the blowback effect of the ignited propellant material towards the expansion chamber through the restricted narrow diameter restricter passageway will be prevented.