EP0738864A1

EP0738864A1 - A 12-gauge shotgun and the like operated by two cylindrical inertial masses slidable along the tubular magazine

Info

Publication number: EP0738864A1
Application number: EP96830225A
Authority: EP
Inventors: Salvatore Tedde
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-04-20
Filing date: 1996-04-19
Publication date: 1996-10-23
Also published as: ITRM950253A0; ITRM950253A1; IT1306600B1

Abstract

A device controlling the breech-block of a shotgun, especially a 12-gauge shotgun, includes two cylindrical lined up inertial masses which are free to slide with respect to each other and to the shotgun along the tubular magazine located under the barrel, the mass remote from the shotgun butt being pivotally connected to a first class lever acting on the breech-block, the other mass being capable of moving said first class lever to release the- breech-block, the displacement of the first inertial mass being impeded by an elastic member or counter spring which is capable of being compressed against a solid member of the shotgun, when the recoil energy overcomes a predetermined threshold, so that the lever controlling the breech-block is driven by the second mass in a more or less delayed way depending on the power of the used cartridge.

Description

The present invention relates to the fire-arms for hunting, sport and defence, particularly to portable fire-arms such as the versatile 12-gauge shotguns, and provides an automatic device for controlling the breech-block so as to anticipate or to delay the opening of the latter as a function of the power of the used cartridge, to the safety of the shot.
Portable fire-arms of the present state of art stand out because of the mechanical operation as follows:

a) the socalled "gas taking" shotguns which uses a fraction of the gases produced at the shot during the combustion of the gunpowder along the barrel for generating the impulse (pressure) necessary for the automation of the resetting cycle for the next shot;
b) the socalled "long barrel recoil" shotguns, in which the barrel and the breech-block integral with each other and connected by a mechanical lock recoil until the breech-block is locked in the opening position; the barrel return to the original position under the thrust of a counter spring which is loaded by the recoil of barrel and breech-block assembly; the breech-block is released in its closed position so that the shotgun is ready for the next shot;
c) the socalled "inertial" shotguns, in which the entire arm recoils at the shot against a solid inertial mass which is located at the rear side of the breech-block and tends to keep still due to inertia. In such step, a fraction of the kinetic recoil energy is stored into a compression spring which stretches out and transmits the stored kinetic energy to the mass which then moves and releases the breech-block which opens the breech.

Notwithstanding the efficiency and the reached degree of reliability of the known types of shotguns described above, no satisfactory solution has been provided yet as far as the breech-block release quickness with regard to the more or less powerful munitioning classes is concerned, thus causing undoubted safety problems to the shot.
The release of the breech-block, which is the mechanical member capable of steadily closing the breech, should always be carried out at a proper moment, i.e. in that very instant in which the pressure in the barrel decreases to the safety level, i.e. neither earlier nor later, on pain of a wrong functioning.
A first object of the present invention is that of overcoming the problems mentioned above and providing a device capable of dynamically controlling the release of the breech-block as a function of the recoil energy, which is different according to the power of the used munitions. Another object of the present invention is that of providing a device controlling the breech-block and capable of anticipating or delaying the closure of the latter as a function of the used cartridges.
Still another object of the present invention is that of providing a device controlling the breech-block of the above-mentioned type which does not need any cleaning operation otherwise necessary against deposits due to external factors.
According to the present invention such objects are achieved by providing a device controlling the release of the breech-block of the shotgun comprising two lined up, cylindrical, inertial masses slidable along the tubular magazine located under the barrel, one of which is pivotally connected to a first class lever acting on the breech-block, the other one is capable of moving said first class lever to release the breech-block, said inertial masses being lined up to an elastic member or counter spring which is capable of delaying the release of said breech-block.
The operation principle is based upon the fact that in case of fire-arms the burned gases push at the shot to opposite directions, on one side, the bullet and, on the other side, the arm which then gains a speed (recoil) and consequently a kinetic energy, the recoil speed being only a fraction of the instant speed of the bullet which is equal to the reverse ratio between the respective masses. According to the invention, the two cylindrical masses which are free to slide with respect to each other and to the shotgun tend to keep still because of inertia upon recoiling of the arm. Therefore, both cylindrical masses move with respect to the shotgun during the recoil step. The displacement of the first cylindrical mass contacting the spring will be more or less extensive depending on the recoil energy as the inertia of such mass is capable of either compressing the spring more or less strongly or not at all. Accordingly, the displacement of the second cylindrical mass in order to drive the breech-block control lever pivotally connected to the first mass is depending on the recoil energy and then the power of the used cartridge. In other words, the inventive step is that of extending the displacement of the first cylindrical mass by shifting the second mass according to the recoil energy in order to differentiate the breech-block controlling times.
Further features and advantages of the invention will be more readily apparent from the following description with reference to the accompanying drawings which illustrate only by way of example a preferred, non-limiting embodiment of the invention, In the drawings:

Fig. 1 shows schematically the device of the invention divided into its main components;
Fig. 2 shows the device of the invention assembled in the shotgun and connected to the breech-block;
Fig. 3 shows the device of the invention in stillstand position;
Fig. 4 shows the device of the invention in working position in case of a light-charge cartridge;
Fig. 5 shows the device of the invention in working position in case of a medium-charge cartridge;
Fig. 6 shows the device of the invention in working position in case of a heavy-charge cartridge.

Referring to the figures, the breech-block control device according to the invention essentially includes a first hollow metal cylinder 10 which is slidable coaxially to tubular magazine 12 located under the barrel, a second cylinder 14 having the same mass as the first one and located in a forward position, i.e. further off the shotgun butt. A first class lever 18 is pivotally connected to tailpiece 16 of such second cylinder having a smaller section, and a large spring 20 which can be suitably calibrated is located before the second cylinder and may be compressed against a solid member 21 integral with the shotgun.
Tailpiece 16 of cylinder 14 can be received by a housing 22 formed at the end of cylinder 10 facing cylinder 14. Such end of cylinder 10 is bevelled at the upper side with respect to the lower side engaging the lower arm 18b of lever 18. The upper arm 18a of lever 18 controls the opening of the breech-block through a rod 24.
The operation of the device will now be described with reference to different munitioning classes.
It is assumed that a relatively light cartridge is fired, the bullet having a total mass of about 32 grams and the arm about 3500 grams, with the barrel being about 600 mm long.
Under such conditions, the energy of the main recoil due to the bullet, which is shot and is still advancing along the barrel, involves the gun as a whole and is about 1/110 of the bullet energy.
During the shot the entire arm recoils against both cylinders 10 and 14 which tend to keep still due to inertia. Cylinder 10 takes on a forward motion by 4 mm with respect to the shotgun (Fig. 4), thus causing a strong thrust against the lower arm 18b of lever 18. The latter rotates anticlockwise and causes rod 24 controlling the breech-block to shift by about 10 mm with the result of a breech-block release.
At the same time the bullet has travelled along the barrel of the shotgun by a length of about 437 mm which is equal to 110 times the travel of cylinder 10, i.e. the recoil travel. The bullet is then near the muzzle, and the inner pressure of the barrel is already decreased to the safety level. These conditions are ideal to release the breech-block which is then pushed by the residual gases and springs backwards so as to cause the spent cartridge case to be extracted and expelled and a new cartridge to be charged.
It should be appreciated that, when firing a light cartridge, cylinder 14 does not take on any travel motion relative to the shotgun as its inertia is not sufficient to overcome the force opposed by spring 20. Cylinder 14 then recoils integrally with the shotgun.
It will now be described the operation of the device according to the invention when a rather heavy cartridge of about 56 grams (12 Magnum) is fired, the characteristics of the shotgun being unchanged as in the former case. The main recoil involves the shotgun as a whole and the recoil energy associated thereto is about 1/63 of the bullet energy. If the release of the breech-block were controlled by cylinder 10 as described above, i.e. just after 4 mm of travel of the same, the bullet would travel along the barrel by a length of about 250 mm as the travel of the bullet is 63 times the travel of cylinder 10 (recoil travel) when the pressure inside the barrel is still too high. An early release would then be caused which is very dangerous for the shot with imaginable consequences. In order to prevent such danger, it is provided according to the invention that the second cylinder 14 acts, in case of firing rather heavy cartridges such as 12 Magnum, as follows: because of the high kinetic energy of the bullet as well as the resulting speed and the recoil energy, when the gun recoils against both lined up cylinders the latter take on a travel motion relative to the shotgun which causes them to overcome the force of counter spring 20 which is compressed with a maximum travel of 7 mm, as shown in Fig. 6. Cylinder 10 collides with lever 18 of cylinder 14 only in the last 4 mm travel and causes the latter to rotate and then rod 24 to shift and to release the breech-block.
Accordingly, the release of the breech-block is delayed by the time in which the bullet has travelled along the barrel by about 437 mm. The latter length corresponds to about 62 times the travel of both cylinders (i.e. the recoil travel) which in this case is the maximum travel. The bullet is near the muzzle when the pressure inside the barrel is decreased to a safety level. That is the time to release the breech-block which springs up backwards and automatically performs its residual functions.
It should be finally taken into account the case in which a medium-weight cartridge is fired, the bullet having a weight of about 44 grams.
The shotgun recoils against both cylinders 10 and 14 as in the former case because of the moderate supplied energy, however, the cylinders travel after each other by an intermediate length of 5,5 mm (Fig. 5) and compress spring 20, thus delaying the release of the breech-block to a lower extent than the former case. Actually, the opening of the breech-block is dynamically related to the supplied energy. At the same time, the bullet has travelled along the barrel by a length of about 437 mm, which corresponds to about 80 times the travel of the cylinders (recoil travel) when the pressure inside the barrel is about to go down as in the former case.
A further advantageous feature of the invention is that the steady closure of the breech is ensured under any operation condition and by any 12-gauge munitioning, since the compression of spring 20 is as greater as higher the initial momentum of bullet. However, the opening of the breech, above all by using heavy cartridges, can only be carried out after spring 20 is duly compressed, i.e. when the pressure inside the barrel is about to go down. Another advantageous feature of the invention is that it is not necessary to use a specific breech-block as the state of art makes use of suitable members capable of being controlled by the described device.
It should be noted that in order to ensure a better effectivenness to the subjected device the cylinders may be suitably lightened by drilling radial holes so as to change the weight ratios and to achieve an inertia capable of differently resist to the force of the spring to specifically fit the used cartridge.

Claims

A device controlling the breech-block of a shotgun, wherein it includes two cylindrical lined up inertial masses which are free to slide with respect to each other and to the shotgun along the tubular magazine located under the barrel, the mass remote from the shotgun butt being pivotally connected to a first class lever acting on the breech-block, the other mass near the shotgun butt being capable of moving said first class lever to release the breech-block, said inertial masses being lined up to an elastic member or counter spring which is capable of being compressed against a solid member integral with the shotgun and is suitably calibrated to delay the release of said breech-block when the recoil energy overcome a predetermined threshold depending on the amount of the recoil energy.
The control device of claim 1, characterized in that the elastic means or counter spring (20) impedes the displacement of the inertial mass carrying the breech-block control lever with respect to the shotgun in a more or less strong way depending on the recoil energy so that the control of said lever by the other inertial mass is automatically executed in a more or less delayed way depending on the power of the used cartridge.
The control device of the preceding claims, characterized in that said inertial mass have a cylindrical shape and may be lightened by radial holes in order to modify the weight ratios in different ways.
The control device of the preceding claims, characterized in that the steady closure of the breech is ensured under any operation condition and by any chosen munitioning, since the compression of the spring (20) is as greater as higher the initial momentum of the bullet, and that the opening of the breech, above all by using heavy cartridges, can only be carried out after the spring (20) is duly compressed, i.e. when the pressure inside the barrel is about to go down.
The control device of the preceding claims, characterized in that the cylindrical inertial mass (14), which is located in a further position than the other mass with respect to the shotgun butt, has at the rear side a projecting tailpiece (16) of lower section, to which a first class lever (18) is pivotally connected, the upper arm (18a) of said lever controlling the opening of the shotgun breech-block through a rod (24).
The control device of the preceding claims, characterized in that the cylindrical inertial mass (10) has a housing (22) capable of receiving said tailpiece (16) at the end facing the other cylindrical mass (14), said end of cylindrical mass (10) being bevelled from the lower to the upper side, the lower side controlling the lower arm (18b) of lever (18).