AND FINAL RETIGHTENING

The invention relates to shotguns .

The shots of a shotgun's charge , immediately after leaving the barrel , form a bunch cluster , the diameter of which expands as its distance from the shotgun increases . From a certain point and after that , the diameter of this bunch cluster increases so that within the shot pattern empty spaces are formed , such that the shot charge is no longer effective as the target , when these empty spaces become larger than that , can no longer be hit . For this reason , at the last before the exit front part of the internal of shotgun barrels there is a constriction , i.e. reduction of the internal diameter in the muzzle area in relation to the rest of the barrel bore , in order to tighten the shot charge so that the shot pellets maintain the effective density of their pattern without gaps etc. at a longer distance from the muzzle than the one at which they would had lost it due to significant spread if there was no the constriction at the exit . This constriction varies depending on the distance at which is sought to be achieved the most effective in its density shot pattern diameter , from negative to small for shots at short distances , moderate for shots at medium distances and great for shots at long distances , with all intermediate gradations according to the intended use of each shotgun .

In recent decades , the part of the interior of the barrels at which there is the constriction is interchangeable , ie before the exit of the barrel there is internally a placement slot , at which is placed interchangeable cylindrical tube with fixation screw thread , which has internally the at each time desired by the user of the weapon constriction .

During the phase of detonation , the shot charge is accelerated within a few milliseconds from zero to hundreds of meters per second , with the result , in its course through the barrel bore , a number of shot pellets , due to the high pressure which develops between them , to undergo cold type welding and form aggregates consisting of 2 or more shot pellets . These aggregates , as they do not have spherical shape , in the course of the shot charge in the air after its exit from the barrel , are diverted from the desired path to the target , thereby reducing the effectiveness of the shot . Furthermore , they cause diversion to other nearby them shot pellets , thus worsening even further the reduction of the effectiveness of the shot as they cause bad shot pellet distribution within the diameter of their pattern . The advantages of the present invention is that is achieved the split of the aggregates of shot pellets before leaving the barrel but also ameliorative rearrangement of the shot pellets with result their smoother entrance into the final constriction of the barrel for the formation of the desired diameter of their pattern , something that is not happening with the hitherto existing interchangeable choke tubes for the shot load of shotguns and which it has as result the improvement of the distribution of the shot pellets within the diameter of their pattern and consequently of the effectiveness of the shot . In Figure (1 ) is shown in side external view a part of one of the many possible to be designed and constructed shotgun barrel (1 ) which includes its muzzle .

In Figure (2) is shown in side external view one of the many possible to be designed and constructed interchangeable choke tube for the shot load of shotgun (2) with fixation screw thread (3) and with flattened front section (4) which is used as a handle for screwing the fixation screw thread (3).

In Figure (3) is shown in side external view the part of the barrel (1 ) of Figure (1 ) with the interchangeable choke tube for the shot load of shotgun (2) of Figure (2) placed inside it with its flattened front section (4) protruding .

In Figure (4) is shown in side sectional view the part of the barrel (1 ) of Figure (1 ) with one of the many possible to be designed and constructed placement slot (5) for interchangeable choke tubes for the shot load of shotgun (2) .

In Figure (5) is shown in side sectional view the interchangeable choke tube for the shot load of shotgun (2) of Figure (2) with one of the many existing conventional type constriction section (6) of reducing internal diameter. In Figure (6) are shown in side sectional view the part of the barrel (1 ) of Figure (4) with the interchangeable choke tube for the shot load of shotgun (2) of Figure (5) placed in the placement slot (5) .

In Figure (7) is shown in side sectional view one of the many possible to be designed and constructed interchangeable choke tube for the shot load of smoothbore shotgun which causes to the shot load gradually initial tightening of progressive form , expansion and final retightening (7) , featuring initial tightening of progressive form section (8) followed by expansion section (9) and which is followed by final retightening section (10) of the shot load , and in which the initial tightening of progressive form section (8) is formed by inner diameter reduction of conical shape , the expansion section (9) is formed by inner diameter increase of conical shape and the final retightening section (10) is formed by inner diameter reduction of conical shape again . In Figure (8) is shown in side sectional view one of the many possible to be designed and constructed interchangeable choke tube for the shot load of smoothbore shotgun which causes to the shot load gradually initial tightening of progressive form , expansion and final retightening (7) , featuring initial tightening of progressive form section (8) followed by expansion section (9) and which is followed by final retightening section (10) of the shot load , at the beginning of which and before the initial tightening of progressive form section (8) there is a cylindrical section - entrance of shot pellets which is continuation of the interior of the barrel (1 ) and in which the initial tightening of progressive form section (8) is formed by inner diameter reduction of conical shape and towards the exit of the barrel abuts cylindrical section which is interposed between this and the expansion section (9) , the expansion section (9) is formed by inner diameter increase of conical shape and towards the exit of the barrel abuts cylindrical section which is interposed between this and the final retightening section (10) and finally the final retightening section (10) is formed by inner diameter reduction of conical shape again and towards the exit of the barrel abuts cylindrical section which is interposed between this and the muzzle of the barrel (1 ) .

In Figure (9) is shown in side sectional view one of the many possible to be designed and constructed interchangeable choke tube for the shot load of smoothbore shotgun which causes to the shot load gradually initial tightening of progressive form , expansion and final retightening (7) , featuring initial tightening of progressive form section (8) followed by expansion section (9) and which is followed by final retightening section (10) of the shot load , in which the expansion section (9) has the shape of a cylinder with base diameter larger than that of the initial tightening of progressive form section (8) and

consequently the increase of the inner diameter is immediate and not gradual .

In Figure (10) is shown in side sectional view one of the many possible to be designed and constructed interchangeable choke tube for the shot load of smoothbore shotgun which causes to the shot load gradually initial tightening of progressive form , expansion and final retightening (7) , featuring initial tightening of progressive form section (8) followed by expansion section (9) and which is followed by final retightening section (10) of the shot load and in which the initial tightening of progressive form section (8) is formed by curve shaped surface reducing the inner diameter , the expansion section (9) is formed by curve shaped surface increasing the inner diameter and the final retightening section (10) is formed by curve shaped surface reducing the inner diameter again .

To increase the effectiveness of the smoothbore shotguns there is a

constriction at the last before the exit front part of the internal of the barrel (1 ) , i.e. reduction of the internal diameter in the muzzle area in relation to the rest of the bore of the barrel (1 ) , in order to tighten the shot charge so that the shot pellets maintain effective density of their pattern without gaps etc. at a longer distance from the muzzle than the one at which they would had lost it due to significant spread if there was no the constriction at the exit of the barrel (1 ) . This constriction varies depending on the distance at which is sought to be achieved the most effective in its density shot pattern diameter , from negative to small for shots at short distances , moderate for shots at medium distances and great for shots at long distances , with all intermediate gradations according to the intended use of each shotgun . In modern technology shotguns of recent decades , the part of the interior of their barrel (1 ) at which there is the constriction is interchangeable, ie before the exit of the barrel (1 ) there is internally a placement slot (5) , at which is placed interchangeable choke tube for the shot load of shotgun (2) with fixation screw thread (3) , which has internally the at each time desired by the user of the weapon constriction .

It is observed that, during the phase of detonation , because the shot charge , pushed by the gases produced from the combustion of gunpowder is accelerated within a few milliseconds from zero to hundreds of meters per second , a number of shot pellets , due to the very high pressure from behind , undergo cold type welding and form aggregates consisting of 2 or more shot pellets . These aggregates , as they do not have spherical shape , in the course of the shot charge in the air after its exit from the barrel (1) , are diverted from the desired path to the target , thereby reducing the effectiveness of the shot . Furthermore , as they cause diversion to other nearby them shot pellets , worsen even further the reduction of the effectiveness of the shot . The interchangeable choke tube for the shot load of smoothbore shotgun which causes to the shot load gradually initial tightening of progressive form , expansion and final retightening (7) of the present invention achieves the improvement of the effectiveness of the shot as , first , the initial tightening of progressive form section (8) featured applies to the shot charge , as it passes through it , vertical lateral pressure which splits the aggregates of shot pellets and second , the expansion section (9) which follows causes ameliorative rearrangement of the shot pellets as they are deploying in a space with larger diameter and , in this way, and their smoother entrance into the final

retightening section (10) with result the improvement of the distribution of the shot pellets within their pattern during their course after their exit from the barrel

(1 ) .

According to the present invention , the interchangeable choke tube for the shot load of smoothbore shotgun which causes to the shot load gradually initial tightening of progressive form , expansion and final retightening (7) , has internally initial tightening of progressive form section (8) followed by expansion section (9) and which is followed by final retightening section (10) of the shot load . According to the present invention, the initial tightening of progressive form section (8) abuts either the beginning of the interchangeable choke tube for the shot load of smoothbore shotgun which causes to the shot load gradually initial tightening of progressive form , expansion and final retightening (7) , and therefore the entrance of the shot pellets is carried out directly in to it , or a cylindrical section which is the entrance of shot pellets that is before the initial tightening of progressive form section (8) and which is interposed between them .

The initial tightening of progressive form section (8) is formed either by inner diameter reduction of conical shape or by curve shaped surface-es reducing the inner diameter , and abuts either the expansion section (9) or a cylindrical section which is interposed between them .

The expansion section (9) is formed either by inner diameter increase of conical shape or by curve shaped surface-es increasing the inner diameter or has the shape of a cylinder with base diameter larger than that of the initial tightening of progressive form section (8) and abuts either the final retightening section (10) or a cylindrical section which is interposed between them . The final retightening section (10) is formed either by inner diameter reduction of conical shape or by curve shaped surface-es reducing the inner diameter , and abuts either the end of the interchangeable choke tube for the shot load of smoothbore shotgun which causes to the shot load gradually initial tightening of progressive form , expansion and final retightening (7) and therefore the exit of the shot pellets is carried out directly out of it , or a cylindrical section which is the exit of the shot pellets and is after the final retightening section (10) and which is interposed between them .