Cartridge receiving drum construction for gas-tight closure between the drum and the adjacent gun barrel
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates in general to the construction of weapons and, in particular, to a new and useful arrangement for the automatic sealing of an end face of a revolving cartridge holder drum and the adjacent barrel. 
     2. Description of the Prior Art 
     The present invention deals with an improvement in the construction of guns which have revolving drums for cartridges, particularly for revolver guns with high ballistic performances and correspondingly designed ammunition. With such a construction, the interstice between the end of the revolving cartridge drum and the barrel of the gun must be sealed during the firing and this is accomplished by an annular ring seal which is retained in a groove around the cartridge passageways which are defined in the drum and which are directed by the action of the ignited cartridge gases to seal the associated drum with the barrel. This known arrangement provides a long-life sealing system which is simple and reliable in construction and operation and which in use or in action can easily be disassembled and reassembled without special tools or assemblage devices. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, the sealing action is improved by a particular critical construction of the sealing groove which is defined around the cartridge projectile guideways at the face of the drum which is adjacent the barrel. In the construction of the invention, the outer diameter of the annular seal ring which fits into the receiving groove is made approximately 8% larger than the largest case diameter of a cartridge to be fired and the seal ring advantageously has a relatively narrow ring area. 
     In a further development of the invention, each of the seal rings arranged in the drum in circumferentially spaced relationship is subjected to the action of partial streams which are branched from the main gas stream of the drum projectile guideways and which pass as partial streams through a plurality of circumferentially arranged bores of relatively small diameter. There are preferably four equally spaced bores arranged to interconnect the bottom of each groove at the barrel facing end of the drum with the interior projectile guideway at a spaced location from the face. In the preferred form, the small diameter bores which connect to the grooves extend obliquely at a small angle in a direction away from the axis of the projectile guideways of the drums and they interconnect at their inner end to a transverse bore which extends into the guideway at a spaced location from the barrel facing end. The diameter of each of the small diameter bores is advantageously equal to or less than 1.0mm. 
     Aside from the fact that the construction of the present invention has the same advantages as the previously disclosed construction mentioned as prior art in respect to the fact that it is a pending application, the present invention has the further following advantages: 
     Due to the optimum value of approximately 8% by which the outer diameter of the seal ring is larger than the largest case diameter of a cartridge to be fired and which has been determined both by theoretic considerations and practical tests, the drum of the revolver gun can also be designed in an optimum manner. That is, with an outer diameter of the seal ring larger than 8%, the groove into which it is inserted should also be larger. However, such a design would diminish the cross-section between the individual circumferentially distributed projectile guideways in an inadmissible and undesirable manner. The result would be permanent deformations requiring replacement of the defective drum. It is evident that such a result is highly undesirable particularly during use of the weapon in action. The outer diameter of the seal ring if made smaller than approximately 8% of the largest case diameter of the cartridge to be fired would have an equally undesirable result in that the arm would no longer be open. 
     Accordingly, it is an object of the invention to provide an arrangement of the sealing between a revolving drum for cartridges and the associated barrel through which the projectiles of the cartridge are to be fired, wherein the drum face on the side adjacent the barrel is provided with annular grooves containing elastic sealing rings wherein the grooves have an outside diameter of approximately 8% larger than the largest case diameter of the cartridge to be fired. 
     A further object of the invention is to provide an arrangement for the gas-tight closure of a separation interstice of a gun barrel and an associated revolving cartridge receiving drum which is simple in design, rugged in construction and economical to manufacture. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference should be had to the accompanying drawing and descriptive matter in which there is illustrated a preferred embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawing: 
     FIG. 1 is a front elevational view of a rotatable drum for a gun constructed in accordance with the invention; and 
     FIG. 2 is a partial sectional view taken along the line I--I of FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings in particular, the invention embodied therein, comprises a rotatable cartridge receiving drum 1 having a plurality of through bores defining projectile guideways 1e which have internal rifling or guide ribs 1i. The guide ribs 1i extend in an axial direction and provide means for guiding the projectile. The drum 1 is mounted for rotation about a central axis 2. Drum 1 has a barrel facing drum surface 1c with a circular groove 1b concentrically arranged thereon around the guideways 1e and having a larger diameter than the guideways. The circular groove 1b is dimensioned so that its outer diameter is approximately 8% larger than the largest case diameter of the cartridge to be discharged from the firearm. 
     In accordance with another feature of the invention, a plurality of small diameter gas supply passages 1a extend obliquely inwardly from the barrel facing face 1c and diverge in a direction outwardly from the adjacent projectile guideway 1e. The inner ends of the small diameter passages 1a are connected by transverse small diameter bores which extend inwardly from the interior of the guideways to the small bores 1b.  The small diameter bores 1x are substantially perpendicular to the axis 8 of each projectile guideway 1e. An elastic seal ring 6 is positioned in the groove 1b and it is capable of withstanding very high temperatures. 
     While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.