Shotgun pellets with knurled surface

Abstract: Shotgun pellets consist of virtually spherical bodies exhibiting a knurled surface made up of a plurality of protuberances (13) and depressions (14). The tips (15) of the protuberances constitute virtually deformable external surfaces of the pellets. The protuberances (13) may cover the entire surface of the pellet and have a virtually pyramidal shape, the height of these protruberances (13) with respect to the bottom of the depressions (14) being virtually between 0.15% and 20% of the pellet diameter, preferably around 5% and in any case greater than 15µm (micrometer). The pellet may be made from soft iron with Vickers hardness between 80 and 120 HV, preferably between 90 and 100 HV.

Description: The present invention relates to pellets used in the production of shotgun shells. In the prior art, shotgun shells are charged with small lead pellets with smooth surface. Thanks to their high ductility and high specific weight lead pellets give satisfactory results in terms of wear of the internal surface of the barrel, shooting accuracy and kinetic energy. In addition, once the target is reached the ductility of the lead causes the pellets to discharge part of their kinetic energy through deformation upon impact with the hard portions of the target without dangerous rebounding in other directions. Lead pellets however exhibit the shortcoming of constituting an element incompatible with some types of terrain on which they fall. The need for replacing the lead of the pellets with another material is considered urgent. Technology has thus suggested the production of shells with a smooth-surface iron pellet charge. Iron pellets exhibit however numerous shortcomings which are the result of the different physical characteristics of the metal. In particular, the high surface hardness of the pellets with respect to lead is such as to cause significant wear of the internal surface of the barrel and in particular in its tapered portions, such as the breach union and muzzle, in particular when the barrel is choked. The rigidity of the iron pellets furthermore has for a result that when they strike hard obstacles they rebound in other directions while keeping high kinetic energy and thus constitute a serious danger for other persons in the area. Another shortcoming of iron pellets is their slighter ballistic stability during flight because of the smaller specific weight of iron in respect of lead, which translates into a greater velocity drop and thus less energy of the individual pellet for equal shooting distance. Finally, the smooth surface of the pellets does not allow satisfactory bunching thereof after explosion of the charge, i.e. assumption by the pellets after firing of a correct arrangement inside the barrel to ensure regularity of the cluster and thus prevent contact between the pellets in flight to improve shooting effectiveness and accuracy. Pellets have been made by forming depressions in their external surfaces (as shown in the US Patent No. 4, 173, 930) for achieving a good ballistic stability. However, the deformability of the pellet is ever entrusted to the ductility of the lead. The general purpose of the present invention is to obviate the above mentioned shortcomings by making available an iron pellet for shotgun shells which would ensure satisfactorily low wear of the internal surface of the barrel. Another purpose of the present invention is to provide a pellet which, upon impact with the hard portions of the target, would have acceptably low rebound aptitude. Another purpose of the present invention is to provide a pellet which would permit high shooting accuracy thanks to good ballistic stability and good bunching capacity of the pellets contained in the shell at the time of shooting. In view of the above mentioned purposes it is sought to provide a shotgun shell pellet according to claim 1. To clarify the explanation of the innovative principles of the present invention and its advantages compared with the known art there is described below with the aid of the annexed drawings a possible embodiment thereof by way of non-limiting example applying said principles. In the drawings: Fig. 1 shows a schematic view of a pellet with knurled surface in accordance with the present invention, and Fig 2 shows an enlarged cross-section view of a portion of the pellet of Fig. 1. With reference to the figures Fig. 1 shows a pellet 10 constituting together with a plurality of similar elements the projectile of a shotgun shell. The pellet 10 has a virtually spherical form and exhibits over its entire surface 11 knurls 12 consisting, as may be seen well in Fig. 2, of a plurality of protuberances 13 and depressions 14. Advantageously the protuberances have a virtually pyramidal form. The tips 15 of the protuberances constitute in accordance with the present invention essentially an external surface deformable upon contact with other bodies. The average height of the tips of the protuberances 13 with respect to the bottom of the depressions 14 is advantageously between 0.15% and 20% of the pellet diameter and preferably around 5%. This height is in any case greater than 15µm. The pellets can advantageously be provided (e.g. by rolling between two knurled surfaces) in soft iron with Vickers hardness between 80 and 120 and preferably between 90 and 110. Upon shooting, in case of dynamic sliding contact with other bodies such as for example the internal surface of the barrel (especially at the cross section reductions at the mouth and, if any, the choke), the tips of the protuberances 13, formed in accordance with the present invention, can easily undergo deformation or abrasion. In this manner the aggressiveness of the pellets toward the above mentioned bodies is considerably reduced. In addition, the deformability of the surface identified by the tips 15 has the result that, upon impact with a target, part of the kinetic energy in play is absorbed by the deformation of the protuberances 13 to reduce significantly the residual energy of the pellets in case of rebound. The protuberances 13 and depressions 14 also contribute to ballistic stability of the pellets during flight to achieve a significant increase in shooting accuracy. It has also been found that such a surface shape of the pellets improves bunching thereof in the barrel upon explosion of the charge. It is thus seen that by provision of pellets in accordance with the present invention the preset purposes are achieved. The arrangement of the protuberances and depressions on the surface of the pellet could be different from that shown. In particular, in addition to the pointed protuberances arranged randomly, the knurling could be configured along parallel or crossed lines. In addition, the pellets with surface form in accordance with the present invention could be provided in materials different from iron. For example, the knurling could be achieved by means of galvanic coating or addition of materials such as Teflon, paint or some other provided their roughness supplied the characteristics of surface deformability of the pellet.

Claims: Shotgun shell pellet consisting of a virtually spherical body having a knurled surface covering the entire surface thereof characterized in that the knurled surface consists of a plurality of tapered protuberances (13) and depressions (14) with the tips (15) of the protuberances constituting an essentially deformable external surface of the pellet. Pellet in accordance with claim 1 and characterized in that the protuberances (13) have a virtually pyramidal shape. Pellet in accordance with claim 1 and characterized in that the height of the protuberances (13) with respect to the bottom of the depressions (14) is virtually between 0.15% and 20% of the pellet diameter and preferably around 5% and in any case greater than 15µm. Pellet in accordance with claim 1 and characterized in that it can be provided in iron with Vickers hardness between 80 and 120 and preferably between 90 and 110.

Inventors: GALLUZZI CARLO, GALLUZZI, CARLO
Applicants: FIOCCHI MUNIZIONI SPA
Application year: 1995
Main classification: F42B7
IPC codes: B22F1, F42B7