GB2310710A - Improvements in or relating to airguns - Google Patents

Abstract

An airgun includes a sliding bolt 12 which is movable from a charging position, where a pellet 20 may be placed in front of the bolt, to a loaded position where the pellet is pushed into the breech 10 of the gun, and is located in front of a gas inlet port 22 through which compressed air or other gas may be introduced into the breech. The sliding bolt may then be returned to the charging position, where a second pellet 21 may be placed in front of the bolt, the bolt then being moved to a intermediate position where the second pellet is pushed into the breech so as to be located between the gas inlet port 22 and the end of the breech, which is sealed by the bolt 12. After the first pellet 20 has been discharged, the bolt may be advanced to the loaded position, thus pushing the second pellet 21 in front of the gas inlet port 22 where it, in turn, may be discharged. In an alternative arrangement (figures 2 to 7, not shown), a second gas inlet port (25) may be located behind the second pellet. A third pellet may be located behind the second inlet port.

Description

"Improvements in or relating to airguns" The invention relates to breech-loading airguns of the kind where a pellet, dart or other projectile to be fired is pushed into the breech end of the barrel of the gun by a sliding bolt which is movable from a charging position, where the projectile may be placed in front of the bolt, to a loaded position where the projectile is disposed within the breech, means being provided to seal the end of the breech behind the projectile, after which gas under pressure is introduced into the breech through a gas inlet port located between the projectile and the sealed end of the breech to propel the projectile along the barrel. The gas may comprise a reservoir of compressed air or other gas which is built into the gun and which is recharged from time-to-time from a main source of the compressed gas. However, the present invention does not exclude airguns where the compressed gas is supplied from a disposable pre-charged cylinder of compressed gas which is attached to the gun, or where the gas, usually air, is compressed by manual operation of a compression device.

The process of loading a fresh projectile into such an airgun takes a certain amount of time, and although the gun may be re-loaded speedily with practice, the time taken may be critical when the gun is used for hunting live game and may be sufficient to allow the quarry to escape, perhaps wounded.

Attempts have been made to speed up the firing rate of airguns by providing a magazine of stacked projectiles which are fed automatically to the breech of the gun.

However, such magazine arrangements tend to be fairly complex, and hence costly and liable to jamming. Also, the lead pellets tend to become deformed as a result of the pressure to which they are subject, both in the magazine and when being fed to the breech of the gun, with the result that they may not properly fit the barrel of the gun when fired, resulting in reduction in velocity of the pellet and consequent loss of power and accuracy.

In any case, for the purposes of hunting it is only the ability to get off a second or third shot in rapid succession which is critical for success, and there is not usually any requirement for the rapid fire of a succession of shots as provided by a magazine system.

The present invention therefore sets out to provide a new form of breech-loading airgun which can allow just a few shots, usually two or three, to be fired in quick succession reliably and without any loss of power of accuracy.

According to the invention there is provided an airgun of the kind first referred to above wherein there is sufficient space in the breech between said gas inlet port and the sealed end of the breech to receive a second projectile, and wherein the sliding bolt is movable from said charging position, where the second projectile may be placed in front of the bolt, to an intermediate position where the second projectile is located in said space in the breech between said inlet port and the sealed end of the breech.

An airgun according to the invention may be referred to as a twin-action single express airgun.

Means are preferably provided for indicating when the sliding bolt is in the intermediate position. For example, a part movable with the sliding bolt may be engageable with a detent, which is fixed in relation to the breech, to retain the bolt in the intermediate position. Similarly, the part movable with the bolt may be engageable with a further detent to retain the bolt in the loaded position.

Thus, alter the first and second projectiles have been introduced into the breech, the first projectile is fired by introducing a charge of gas under pressure through the gas inlet port, after which the sliding bolt is moved to the loaded position again to move the second projectile to the loaded position where it is in front of the gas inlet port.

Introduction of a second charge of gas under pressure through the port fires the second projectile.

Altematively, the breech may be provided with a second gas inlet port located between the space for the second projectile and the sealed end of the breech, so that the second projectile may be fired by introducing a charge of gas under pressure through said second gas inlet port, valve means being provided to open one or other of said gas ports selectively.

The valve means to open the gas ports is preferably coupled to the trigger mechanism of the airgun so that movement of the trigger to a first position opens the first gas inlet port, to fire the first projectile, and subsequent movement of the trigger to a second position opens the second gas inlet port to fire the second projectile.

In the case where a second gas inlet port is provided, there may be provided sufficient space between the second gas inlet port and the sealed end of the breech to receive a third projectile, the sliding bolt then being movable to a second intermediate position, between the charging position and the first said intermediate position, where the third projectile may be introduced into said space between said second gas inlet port and the sealed end of the breech.

Thus, after the first and second projectiles have been fired, the third projectile may be moved by the sliding bolt to a position in front of the first gas inlet port, so that it can be fired by introducing a further charge of gas under pressure through that inlet port.

Although, in any of the above arrangements the second, or second and third, projectiles may be adequately retained in the breech by friction, there is preferably provided removable retaining means to retain the second and/or third projectile in its required position in the breech, prior to its being fired. For example, the retaining means may comprise a retaining element which is movable between a position where it projects into the bore in the breech in front of a projectile, and a position where it is withdrawn from the bore. Preferably operation of said retaining element is coupled to operation of the gas control valve to introduce and withdraw the retaining element at the appropriate times.

There may also be provided a vacuum release valve in the wall of the breech to the rear of the first projectile, to permit the entry of ambient air into the breech and barrel in the event that firing of the first projectile induces a partial vacuum within the breech and barrel. Such partial vacuum might otherwise cause displacement of the second projectile along the barrel which might interfere with its subsequent firing. In the case where three projectiles may be introduced into the breech, such a vacuum release valve may also be provided to the rear of the second projectile.

Although the ability to store two or three projectiles in the breech, as described above, may be all that is required for practical purposes, it will be appreciated that the principle of the invention may theoretically be applied to store a greater number of projectiles in the breech of the airgun and the invention does not exclude arrangements where more than three projectiles are stored. However, the number of projectiles which can be stored will in practice be limited by considerations of space and the required complexity of the sliding bolt and gas control valve mechanism.

In any of the above arrangements a part of the sliding bolt itself may constitute the means for sealing the end of the breech. In this case a part of the bolt which is introduced into the end of the breech may be formed with a flexibly resilient sealing element which sealingly engages the internal walls of the breech around the bolt.

In conventional breech-loading airguns of the kind first referred to, the sealing element is usually in the form of a simple rubber or resilient plastics O-ring which is compressed as the end ofthe bolt is forced into the breech end of the barrel. However, constant operation in this fashion leads to wear of the O-ring and such wear is likely to be particularly severe in the case where the breech end of the barrel is rifled so that the O-ring has to be forced into the rifling.

According to an important aspect ofthe present invention, therefore, means may be provided to expand the flexibly resilient sealing element radially into sealing engagement with the walls of the breech, after the sliding bolt has been introduced into the breech. The sealing element may then initially be introduced only comparatively loosely into the breech, thus minimising wear, only subsequently being expanded outwardly into sealing engagement with the walls of the breech, including any rifling grooves in those walls.

The flexibly resilient sealing elements may, for example, comprise a resiliently flexible body of material disposed between two axially spaced abutments on the sliding bolt, means being provided to displace said abutments axially towards and away from one another, whereby the sealing element may be compressed axially, by movement of the abutments towards one another, so as to expand radially outwards into sealing engagement with the walls of the breech.

One of the abutments may be coupled by a screw-thread mechanism to a rotatable operating element on the sliding bolt, whereby rotation of the operating element effects axial displacement of said abutment to compress the sealing element axially.

In a preferred embodiment of the invention, said rotatable operating element is coupled to the aforesaid part which is engageable with a detent to retain the bolt in the loaded and/or intermediate positions. For example, the rotatable operating element may be formed with a projecting arm which may be rotated through an angle into engagement with a fixed retaining slot, to prevent further axial movement of the bolt, in the loaded and/or intermediate positions of the bolt. Thus, rotation of the arm to lock the bolt in a required firing position then automatically and simultaneously expands the sealing element to seal the end of the breech ready for firing.

The expansible sealing arrangement referred to above may also be applied to any other airgun of the kind first referred to, and is not limited to use with airguns according to the present invention.

Accordingly, the invention also includes within its scope a breech-loading airgun where a projectile to be fired is pushed into the breech end of the barrel of the gun by a sliding bolt which is movable from a charging position, where the projectile may be placed in front ofthe sliding bolt, and a loaded position where the projectile is disposed within the breech, means being provided to seal the end of the breech behind the projectile, after which gas under pressure is introduced into the breech through a gas inlet port located between the projectile and the sealed end to project the projectile along the barrel, a part of the bolt which is introduced into the end of the breech being formed with a resilient sealing element, and means being provided to expand the resilient sealing element radially into sealing engagement with the walls of the breech, after the sliding bolt has been introduced into the breech, to provide said sealing means.

The following is a more detailed description of embodiments of the invention, reference being made to the accompanying drawings in which: Figure 1 is a diagrammatic representation of the breech end of an airgun in accordance with one embodiment of the invention, Figures 2-7 are similar views of a second embodiment of the invention, showing the different stages of loading the airgun, and Figures 8 and 9 are diagrammatic representations of a sliding bolt for an airgun according to the invention, showing the expansible sealing arrangement.

The parts of the airgun, which may be a pistol or rifle, not illustrated or described in the following description may be of any of the forms conventionally employed in airguns ofthe basic type first referred to in this specification. The arrangement of firing mechanisms and compressed gas assemblies for such guns, as well as other structural features, are well known and will not therefore be described in detail.

Referring to Figure 1: the breech end of the barrel of an airgun is indicated at 10 and has an internal rifled bore 11. A sliding bolt 12 is axially slidable into and out of engagement with the open end ofthe bore. The end ofthe bolt 12 which passes into the breech is formed with a push rod 13 and an expansible sealing element 14 which, as will be described later, serves to seal the end of the breech in gas-tight manner.

The opposite end of the bolt 12 is formed with a rotatable collar 15 from which projects a radially extending arm 16 which may be rotated into and out of engagement with slots 17 and 18 formed in a guide 19 which is fixed in relation to the breech 10.

The bolt 12 is slidable along a fixed channel (not shown) which partly embraces the bolt and restrains it for longitudinal movement.

For the purposes of illustration the projectiles 20 and 21 to be loaded into the airgun are depicted as simple spheres, although in practice they are likely to be waisted lead pellets, or perhaps darts or other shaped projectiles. For convenience the projectiles will be referred to as pellets in the following description.

The wall of the breech 10 ofthe airgun is formed with a transverse gas inlet port 22. In well known manner the inlet port 22 is connected through a valve (not shown) to a cylinder of pressurised gas, usually air, mounted on the gun. The valve is under the control of the trigger of the gun so that when the trigger is pulled the valve is briefly opened to introduce a charge of gas under pressure into the breech.

In order to load the first pellet 20 into the gun, the arm 16 of the bolt 12 is rotated out of engagement with the slot 17 and the bolt 12 completely withdrawn along its channel from the breech of the gun. The pellet 20 is placed in the channel in front of the bolt 12, and adjacent the open end ofthe breech. The bolt 12 is then slid axially into the end of the breech, pushing the pellet 20 into the breech in front of it. At this stage the sealing element 14 is uncompressed and thus slides comparatively easily into the bore 11.

The bolt continues to be pushed into the breech until the arm 16 comes opposite the slot 18 in the fixed guide 19. In this position of the bolt 12, the first pellet 20 has reached the position shown in Figure 1, that is to say it is in front of the gas inlet port 22. When the arm 16 on the bolt is level with the slot 18 in the guide 19, it may be rotated to enter the slot 18. This would cause the sealing element 14 to expand, as will be described below, and the gun would then be ready to fire the single shot. According to the invention, however, a second pellet 21 is first introduced into the breech so that the two shots may be fired in quick succession.

In order to introduce the second pellet, the bolt 12 is again withdrawn completely from the breech, the second pellet 21 is placed in the channel in front ofthe bolt and the bolt is again introduced into the breech, pushing the pellet 21 in front of it.

This time, however, the bolt 12 is only pushed into the breech sufficiently far for the arm 16 on the bolt to line up with the first slot 17 in the fixed guide 19. This brings the second pellet 21 to the position shown in Figure 1 where it lies behind the first pellet 20 and to the rear ofthe gas inlet port 22. The arm 16 is rotated into engagement with the slot 17. This serves both to retain the bolt 12 axially and also to expand the sealing element 14 to seal the end ofthe breech. The gun is now loaded ready to fire the two shots.

When the trigger is pulled to fire the first shot the valve controlling the inlet port 22 is opened to deliver gas under pressure into the breech and discharge the first pellet 20. At the same time, however, a linkage mechanism, coupled to the trigger and valve, moves a retaining pin 23 so that the inner end of the pin projects from the wall of the breech 10 into the bore 11. The inwardly projecting end ofthe pin 23 serves to retain the second pellet 21 in position to the rear of the gas inlet 22 while the first pellet 20 is fired.

As a pellet being fired approaches the outlet end of the barrel a partial vacuum may be created within the barrel. Not only may this tend to reduce the velocity of the pellet being fired, but it might also tend to displace the second pellet 21 if a retaining device, such as the pin 23, were not provided. In order to compensate for any partial vacuum which occurs, therefore, the wall of the breech 10 is provided with a vacuum release valve 24 which allows for ambient air to be sucked into the breech and barrel in the event that a partial vacuum occurs. The vacuum release valve 24 may also act as a damper to smooth out the recoil due to the firing of the pellet.

Once the first pellet 20 has been fired, the arm 16 on the bolt 12 is rotated out of engagement with the slot 17, the bolt 12 is slid further into the breech and the arm 16 engage with the slot 18. This action, which can be performed very quickly, brings the second pellet 21 to the forward side of the gas inlet 22, the retaining pin 23 having been automatically withdrawn following operation of the trigger and gas control valve. The second pellet 21 may thus then be fired by again pulling the trigger to deliver a further charge of compressed gas to the breech behind the pellet.

Figures 2-7 show a modified arrangement according to the invention by which two pellets may be fired in even more rapid succession and where a third pellet may also be introduced into the breech if required.

In this modified arrangement the wall of the breech end 10 of the barrel is formed with a second gas inlet port 25 located between the first gas inlet port 22 and the end of the breech The fixed guide 19 is provided with a third slot 26. Other components bear the same reference numerals as in the arrangement of Figure 1.

In order to load the first pellet 20 and second pellet 21, the procedure is the same as in the description ofthe Figure 1 arrangement. That is to say, when the first pellet 20 is loaded the bolt 12 is pushed until the arm 16 can engage the slot 18, and the second pellet 21 is loaded (as shown in Figure 3) by pushing in the bolt 12 until the arm 16 can engage with the slot 17. As may be seen from Figure 3, in this position the second pellet 21 is to the rear ofthe first gas inlet 22 but in front ofthe second inlet 25.

In order to load a third pellet 26 into the breech, the bolt 12 is inserted to a position where the arm 16 on the bolt can be engaged with the third slot 32 in the guide 19, as shown in Figure 4.

The slots 17 and 18 serve merely to indicate the extent to which the bolt must be introduced into the breech to load the first and second pellets. The slots 17 and 18 are so arranged that the rotation of the arm 16 to engage the slots may be less than is required to expand the sealing element 14 into firm engagement with the walls of the bore, so that the free sliding movement of the bolt is not inhibited. The slots 17 and 18 could, indeed, be replaced by simple indicating marks on the guide 19 to indicate the extent to which the bolt should be moved. However, it is found in practice that it is easier to move the bolt to the appropriate position if it requires to engage a positive detent device.

The slot 32, on the other hand, requires greater rotation of the arm 16 before it is engaged, and such greater rotation expands the sealing element 14 so as to seal the end of the breech in gas-tight manner, as shown in Figure 4. The gun is now ready to fire the three shots in quick succession.

The first and second gas inlet ports 22, 25 are controlled by a valve system which is, in turn, so controlled by the trigger mechanism that, in a-first position to which the trigger is pulled, the first port 22 is opened while the second port 25 is closed, as shown diagrammatically in Figure 5. The charge of gas under pressure thus enters the breech to the rear of the first pellet 20 but in front of the pellets 21 and 26, so discharging the first pellet 20 from the gun.

If the trigger is then subsequently pulled to a second position, the inlet port 22 is closed and the second inlet port 25 opened, as shown diagrammatically in Figure 6, so that the second pellet 21 is discharged from the gun while the third pellet 26 is retained.

The trigger is then released and the bolt 12 is advanced until the arm 16 can be engaged in the slot 18, thus moving the third pellet 26 to the position shown in Figure 7, where is lies in front of the inlet port 22. The trigger is then pulled to its first position again, opening the port 22 while the port 25 remains closed. The third pellet 26 is thus discharged from the gun.

The arrangement thus allows two pellets to be fired off in very quick succession, merely by two successive pulls on the trigger, while the third pellet can be fired also after a very quick movement of the bolt.

The arrangement of Figures 2-7 may also be provided with retaining pins linked to the rest ofthe mechanism, to retain the second and third pellets in position while the previous pellet is fired, in similar fashion to the retaining pin 21 of Figure 1. Similarly vacuum release valves may be located in the walls of the breech between the first and second pellets and between the second and third pellets.

Also, in the arrangement of Figures 2-7, it may be advantageous to provide in the walls of the breech a gas channel connecting the space in front of the second pellet 21 to the space behind it. This channel will then tend to equalise the gas pressures on the two sides of the second pellet and prevent it being moved backwards as the first pellet is discharged. The flow along the gas channel may be controlled by an adjustable valve screw.

It will be appreciated that the arrangement of Figures 2-7 may be used only to fire the first and second pellets in quick succession and it is not necessary to introduce the third pellet into the breech if this is not required. Thus in a modified version the third slot 32 could be omitted so that only two shots are fired in succession. In this case the two shots would be fired in the position shown in Figure 3 and the engagement of the arm 16 with the slot 17 would be such that the seal 14 would seal the end of the breech when in this position.

It will be appreciated that the arrangement of Figures 2-7 could be modified so that more than three pellets could be stored in the breech and fired in succession.

However, this would require a correspondingly greater number of appropriately positioned gas inlet ports, and valve means arranged to open the appropriate ports in succession. This would add to the complexity of the mechanism, and the space required to accommodate more than three pellets in the breech would necessitate further elongation of the breech and of the bolt 12.

Figures 8 and 9 show in greater detail one possible form of construction for the resilient sealing arrangement on the bolt 12.

In this case the bolt 12 comprises a main cylindrical part 27 through which passes an axially slidable rod 28. One end ofthe rod 28 provides the pusher 13 for engagement with the pellets, and adjacent the pusher 13 is an abutment disc 29. A collar 20 of rubber or other resiliently flexible material encircles the rod 28 between the disc 29 and main part 27 of the bolt. The opposite end 31 of the rod 28 is in threaded engagement with the collar 15 on which the arm 16 is mounted.

In its relaxed position the resiliently flexible collar 30, as shown in Figure 8, does not bear against the walls of the bore in the breech. When the arm 16 is rotated fully into engagement with the appropriate slot in the guide 19, however, the consequent rotation of the collar 15 on the threaded end 31 of the rod draws the rod 28 axially through the main part 27 ofthe bolt, compressing the resilient collar 30 between the disc 29 and the main part 27 of the bolt. The periphery of the collar 30 thus bulges out radially, as shown in Figure 9, so as sealingly to engage the walls of the bore in the breech. It will be appreciated that the main part 28 of the bolt requires to be restrained against rotation when the arm 16 and collar 15 are rotated.

Although the expanding seal arrangement described above is preferred, it will be appreciated that it is not essential to the invention and the bolt could instead use conventional O-ring seals. Similarly, the described expansion seal could be used with other more conventional airguns and is not limited to use with the two shot or three shot airgun according to the present invention.

Although the provision of the retaining pins, or similar restriction devices, is preferred they are not essential to the invention and in some cases the friction between the pellets and the barrel may be sufficient to retain them in position. Similarly, the provision the vacuum release valve is not essential.

Claims (20)

1. An airgun including a sliding bolt which is movable from a charging position, where a projectile may be placed in front of the bolt, to a loaded position where the projectile is disposed within the breech ofthe gun, means to seal the end of the breech behind the projectile, and means for introducing gas under pressure into the breech through a gas inlet port located between the projectile and the sealed end ofthe breech to propel the projectile along the barrel, wherein there is sufficient space in the breech between said gas inlet port and the sealed end of the breech to receive a second projectile, and wherein the sliding bolt is movable from said charging position, where the second projectile may be placed in front ofthe bolt, to an intermediate position where the second projectile is located in said space in the breech between said inlet port and the sealed end ofthe breech.

2. An airgun according to Claim 1, wherein means are provided for indicating when the sliding bolt is in the intermediate position.

3. An airgun according to Claim 2, wherein a part movable with the sliding bolt is engageable with a detent, which is fixed in relation to the breech, to retain the bolt in the intermediate position.

4. An airgun according to Claim 3, wherein the part movable with the bolt is engageable with a further detent to retain the bolt in the loaded position.

5. An airgun according to any of the preceding claims, wherein the breech is provided with a second gas inlet port located between the space for the second projectile and the sealed end of the breech, so that the second projectile may be fired by introducing a charge of gas under pressure through said second gas inlet port, valve means being provided to open one or other of said gas ports selectively.

6. An airgun according to Claim 5, wherein the valve means to open the gas ports is coupled to the trigger mechanism ofthe airgun so that movement ofthe trigger to a first position opens the first gas inlet port, to fire the first projectile, and subsequent movement ofthe trigger to a second position opens the second gas inlet port to fire the second projectile.

7. An airgun according to Claim 5 or Claim 6, wherein there is provided sufficient space between the second gas inlet port and the sealed end of the breech to receive a third projectile, the sliding bolt then being movable to a second intermediate position, between the charging position and the first said intermediate position, where the third projectile may be introduced into said space between said second gas inlet port and the sealed end ofthe breech.

8. An airgun according to any of the preceding claims, wherein there is provided removable retaining means to retain the second projectile, and/or third projectile, in its required position in the breech, prior to its being fired.

9. An airgun according to Claim 8, wherein said retaining means comprise a retaining element which is movable between a position where it projects into the bore in the breech in front of a projectile, and a position where it is withdrawn from the bore.

10. An airgun according to Claim 9, wherein operation of said retaining element is coupled to operation of the gas control valve to introduce and withdraw the retaining element at the appropriate times.

11. An airgun according to any of the preceding claims, wherein there is provided a vacuum release valve in the wall of the breech to the rear of the first projectile, to permit the entry of ambient air into the breech and barrel in the event that firing of the first projectile induces a partial vacuum within the breech and barrel.

12. An airgun according to Claim 11, and where a second vacuum release valve is also be provided to the rear ofthe second projectile.

13. An airgun according to any ofthe preceding claims, wherein a part ofthe sliding bolt itself constitutes the means for sealing the end of the breech

14. An airgun according to Claim 13, wherein a part ofthe bolt which is introduced into the end of the breech is formed with a flexibly resilient sealing element which sealingly engages the internal walls of the breech around the bolt.

15. An airgun according to Claim 14, wherein means are provided to expand the flexibly resilient sealing element radially into sealing engagement with the walls of the breech, after the sliding bolt has been introduced into the breech.

16. An airgun according to Claim 15, wherein the flexibly resilient sealing element comprises a resiliently flexible body of material disposed between two axially spaced abutments on the sliding bolt, means being provided to displace said abutments axially towards and away from one another, whereby the sealing element may be compressed axially, by movement of the abutments towards one another, so as to expand radially outwards into sealing engagement with the walls ofthe breech.

17. An airgun according to Claim 16, wherein one ofthe abutments is coupled by a screw-thread mechanism to a rotatable operating element on the sliding bolt, whereby rotation of the operating element effects axial displacement of said abutment to compress the sealing element axially.

18. An airgun according to Claim 17, wherein said rotatable operating element is coupled to the aforesaid part which is engageable with a detent to retain the bolt in the loaded and/or intermediate positions.

19. An airgun according to Claim 18, wherein the rotatable operating element is formed with a projecting arm which may be rotated through an angle into engagement with a fixed retaining slot, to prevent further axial movement of the bolt, in the loaded and/or intermediate positions of the bolt.

20. An airgun including a sliding bolt which is movable from a charging position, where a projectile may be placed in front of the bolt, to a loaded position where the projectile is disposed within the breech of the gun, means to seal the end of the breech behind the projectile, and means for introducing gas under pressure into the breech through a gas inlet port located between the projectile and the sealed end of the breech to propel the projectile along the barrel, wherein a part ofthe bolt which is introduced into the end of the breech is formed with a resilient sealing element, and means are provided to expand the resilient sealing element radially into sealing engagement with the walls of the breech, after the sliding bolt has been introduced into the breech, to provide said sealing means.