Abstract:
This invention concerns a supplementary safety device in the form of a false cartridge to be inserted into the chamber of a light firearm barrel, including a radially expandable portion controlled by a lock operated by a specific key for locking/unlocking it in the barrel in which it is housed, so it may be removed only voluntarily.

Description:
INVENTION FIELD 
     This invention concerns, in general, the field of light firearms, both long and short barrelled such as parallel barrel or over-and-under shotguns, rifles, handguns etc., and in particular refers to a safety device for these arms, namely a mechanical supplementary safety device in the form of a false cartridge. 
     STATE OF THE ART 
     On the one hand the use of so-called false cartridges is already established: devices inserted into the chamber of the barrel(s) of a light firearm when it is not in use, in place of a real cartridge, with view to at least preventing the gun going off accidentally and indicating that it cannot be arbitrarily used. These means however have no real safety device function in the sense that they cannot effectively block abusive use of the firearm since the false cartridge may easily be removed without specific tools even by a child or by unauthorised and incompetent persons. 
     On the other hand, though the firearms mentioned above are usually equipped with safety catches with the function of preventing them going off accidentally, for example by blocking the trigger mechanism and/or the hammer action, today there is a pressing demand and consequent need to equip these arms with an additional safety device that can be activated and deactivated by a personalised means available only to the owner of the firearm or someone delegated thereby, thus avoiding effective use of the firearm by unauthorised persons. 
     PURPOSES AND SUMMARY OF THE INVENTION 
     One purpose of this invention is to offer a supplementary safety device created in the form of a false cartridge which can be inserted and stably locked in the chamber of light firearms without the possibility of removal other than voluntary and only by using a specific means correlated to the device itself. 
     Another purpose of the invention is to supply a mechanical safety device that fully corresponds to the current, sought-after requirement of increased safety in the use of light firearms such as to permit their use only and exclusively to those who have a personalised method, such as a key, that can control and remove the device once the latter has been activated. 
     A further purpose of the invention is to create and supply a safety device for light firearms, shotguns, rifles, handguns and similar that is supplementary to the safety catches with which these firearms are already equipped. 
     Yet another purpose of the invention is to supply a safety device for the above mentioned firearms that has two distinct locking sections for maximum efficiency: the first section can be voluntarily activated and deactivated by a specific and personalised method, while the second section, normally inactive, is activated following surreptitious attempted breakage and removal of the device when it is locked in the barrel of a firearm. 
     The invention achieves these purposes with a mechanical safety device for light firearms, with a first body including a lock with a rotating part controlled by a specific key. A second body is linked to the first body and is axially movable with respect to the second body without rotating with respect to the second body. The second body is axially movable between a position of unlocking when distant from, and locking when close to, the first body. A screw pin is drivable in rotation in the first body without moving axially in the first body. The screw pin is connected to, and controlled by, the lock for its rotation, and is linked directly or indirectly with the second body for the movement thereof between the positions of unlocking and locking following the turning of the screw pin. A flexible element deformable by compression, is located between the first and second bodies in order to expand radially and project peripherally from the bodies when the second body is in the locking position, thus creating the locking of the device in the chamber of the barrel in which it is housed. 
     Correspondingly, the safety device proposed herewith, substantially in the form of a false cartridge or of a form suitable for insertion into the chamber of a firearm, possesses first of all a radially expandable portion controlled by a lock and specific key for locking/unlocking it in the barrel in which it is lodged, thus making it removable only voluntarily. 
     However, depending on the state and/or the lubrication of the barrel cartridge chamber internal surface, this controlled expansion lock might not prevent the sliding and forced ejection of the device if axial thrust were to be applied by means of a tool such as a rod, inserted into the muzzle of the barrel. 
     So the second locking portion of the device is aimed at preventing all unauthorised forced removal, thanks to an accentuation of the locking action. In fact any axial thrust applied to the device with the intention of ejecting it from the part of its introduction into the barrel results in activation of this second portion which, expanding, tightens against the interior of the barrel; and the greater the thrust the greater the tightening. The advantages of the new supplementary safety device invention may therefore be summarised as follows: 
     great ease, convenience and immediacy of use; 
     maximum efficiency and reliability in preventing unauthorised use of the firearm; 
     possibility of breakage minimised, and even more so if the command lock is 
     made in drill-resistant material. 
     Moreover, its configuration and absence of appendices mean that when the device is set in place in the chamber it offers no part that might be gripped by an extracting tool. Lastly, a safety device of this type may be easily manufactured and adapted with the same efficacy and safety to firearms of all calibres, without any modification of the firearm whatsoever. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described in greater detail below with reference to the attached indicative and not limitative drawings in which: 
     FIG. 1 shows a blow-up view of the elements comprising the device; 
     FIG. 2 shows an analogous blow-up view of the elements of FIG. 1, but in section; 
     FIG. 3 shows an external view of the assembled device; 
     FIG. 4 shows the device in longitudinal section; 
     FIG. 5 shows an external view of the device in a variant version; and 
     FIG. 6 shows the FIG. 5 device in longitudinal axial section; 
     FIG. 7 is a longitudinal sectional view of the assembled device situated inside the barrel of a firearm in a locked state. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The safety device in question is inserted into the chamber of a firearm from the breech towards the muzzle. It consists of a first body  10  pointing towards the breech  28 A of the barrel  28 , a second intermediate body  11  and a final spigot and socket body  12 , this last pointing towards the muzzle  28 B. The first body and the second intermediate body are joined and axially moveable each with regard to the other, but without the possibility of rotation, thanks to an axial appendix  16  integral with the intermediate body and having the purpose of insertion into corresponding housing  17  in the first body. 
     The first body  10  and the intermediate body  11  are joined by a rotating screw pin  13  with head  13 ′ housed in the first body, abutting against a shoulder which impedes axial movement of the pin without obstructing its rotation. The screw pin  13  may be screwed directly to the intermediate body  11  or, as shown in the drawings, to a threaded element  14  associated with that body, in such a way that rotation of the screw pin in one direction causes the approach and in the other direction the distancing of the intermediate body with regard to the first body. 
     An anti-rotation gasket  15  is mounted around the first body  10  to prevent rotation of the device when it is placed in the chamber for use. 
     The contiguous extremities  10 ′ and  11 ′ of the two bodies  10  and  11  respectively are in truncated cone form and extend from the respective shoulders  10 ″ and  11 ″. Together they delimit an annular peripheral housing  18  at which level is envisaged at least one deformable and expandable by compression element such as, for example, a gasket  19  in an elastomer material, a cup spring  20 , or some other element, which is radially squeezed and expanded between the two shoulders  10 ″ and  11 ″ when the two bodies  10  and  11  are brought together. 
     The first body  10  houses and retains a safety lock  21 , linked with the screw pin  13  for rotation of the latter and activated by means of a personalized key supplied to the firearm owner. In the embodiment of FIGS. 2 and 4, the lock  21  has a rotating part  21 A defining a seat  29  for receiving the key. Other lock and key type arrangements are also possible. 
     So when the device is placed in the chamber of a firearm barrel, by turning the screw pin  13  with lock and key in one direction, the intermediate body  11  is brought close to the first body  10  and there is consequent radial expansion of the expandable element  19  or  20 , resulting in the device being locked into the chamber. Thus the device cannot be extracted from the breech and the firearm cannot be used by unauthorised persons or those not in possession of the key. Turning the key and therefore the screw pin in the opposite direction, the device is unlocked. 
     The spigot and socket body  12  is linked to the forward extremity of the intermediate body  11  by the interposing of a spacer  27 . This is axially bound to the free extremity of the screw pin  13 , for example by a Seeger  22 ′, and has a side wall  23  which is winged and expandable and delimits a conical cavity  24 , tapering towards the bottom of the body itself. The cavity contains an axially moveable conical plug  25  and is closed by a cover  26  to prevent exit of the plug. 
     So when the safety device has been locked in the barrel of the firearm with the special key, any action or thrust on the device, perhaps with a rod inserted into the muzzle with view to ejecting the device at the breech, will cause in-depth penetration of the conical plug  25 , consequent expansion of the winged wall  23  of the spigot and socket body against the internal wall of the barrel and an accentuation of the blocking of the device, making it practically immoveable also in such cases. 
     The same result is obtained, as shown FIGS. 5 and 6, when the spigot and socket body is not independent but integrated with or integral to the intermediate body. 
     Lastly it should be noted that as a means of impeding forced and unauthorized ejection of the device from a firearm barrel  28 , the spigot and socket body could be replaced by other elements such as a permanent deformation organ, a conical screw or an inclined sector, without this being a departure from the context of the invention. 
     While specific embodiments of the invention have 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.