Automatic Shotgun Choke

Abstract

A choke attachment for a shotgun barrel to automatically provide an extension of the bore of the barrel upon firing the first round from the shotgun. The attachment consists of a collar clamped on the shotgun barrel and having pivoted barrel segments with outer cam surfaces engagable by a camming sleeve surrounding the segments and urged forwardly by a coiled spring. The camming sleeve is normally held in a rearward position against the force of the coiled spring by detent arms pivoted to the segments which are triggered outwardly by the expansive force produced by the first round fired by the shotgun. The spring then acts on the camming sleeve to force the segments inwardly to define an extension of the shotgun bore and thus provide the desired choke action for subsequent shots.

Description

This invention relates to choke attachments for shotguns and more particularly to a choke attachment to automatically provide an extension of the bore of the barrel of the shotgun upon firing the first round from the shotgun, whereby to provide an increase in shotgun range.

A main object of the invention is to provide a novel and improved choke attachment for a shotgun barrel to automatically extend the range of the associated shotgun without manual adjustment upon firing the first round from the shotgun, the attachment being relatively simple in construction, being easy to install, and having the effect of automatically extending the length of the shotgun barrel on firing the first round at an intended target.

A further object of the invention is to provide an improved choke attachment for a shotgun barrel, the attachment being inexpensive to manufacture, being durable in construction, being reliable in operation, and being arranged so that it can be quickly and easily mounted on a conventional shotgun barrel.

A still further object of the invention is to provide an improved choke attachment for a shotgun barrel for providing an increase in gunshot range without manual adjustment and operating to extend the length of the shotgun barrel automatically upon firing off the first round at an intended target, the attachment being relatively compact in size, comprising only a few parts, being easy to install and set up for use, and providing improved accuracy of the shotgun on which it is employed.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

FIG. 1 is a perspective view of the end portion of a shotgun barrel provided with an improved choke attachment constructed in accordance with the present invention.

FIG. 2 is a longitudinal vertical cross-sectional view taken through the attachment substantially on the line 2--2 of FIG. 1.

FIG. 3 is an enlarged end elevational view of the attachment, taken substantially on the line 3--3 of FIG. 2.

FIG. 4 is an enlarged transverse vertical cross-sectional view taken substantially on the line 4--4 of FIG. 2.

FIG. 5 is an elevational view of the barrel end portion and choke attachment of FIG. 1 with the triggering elements of the attachment released to provide an extension of the bore of the barrel resulting from firing the first round from the associated shotgun.

FIG. 6 is a longitudinal vertical cross-sectional view taken substantially on the line 6--6 of FIG. 5.

FIG. 7 is an enlarged transverse vertical cross-sectional view taken substantially on the line 7--7 of FIG. 6.

Referring to the drawings, 11 generally designates an improved automatically operating shotgun choke device according to the present invention, shown mounted in operating position on the muzzle end portion of the barrel 12 of a conventional shotgun. As shown, the shotgun may be provided on the muzzle end of its barrel with a conventional upwardly projecting front sight 13.

Choke attachment 11 comprises a sleeve-like supporting collar member 14 which is telescopically engagable on and closely receives the muzzle end portion of barrel 12, being formed with a relatively long longitudinally extending rectangular notch 15 to provide clearance for the front sight 13, the collar member 14 being of sufficient length so that it extends rearwardly a substantial distance beyond the front sight 13, as shown in FIG. 5. Collar member 14 is rigidly clamped to the shotgun barrel 12 by a multiple-segment clamping band assembly 16, which may comprise a pair of mating clamping band segments 17, 17 provided with apertured outwardly extending end tabs 18 which are clamped together by clamping bolts 19 in the manner shown in FIG. 5, the assembly 16 being located rearwardly adjacent the front sight 13.

The collar member 14 terminates substantially flush with the forward end of the muzzle 12 and is provided at its forward end portion with a plurality of spaced sets of parallel apertured pivot lugs 20,20, there being three evenly spaced sets of such pivot lugs in a typical embodiment illustrated herein. Respective forwardly extending barrel extension segments 21 are pivotally connected to the collar member 14 by means of transverse pivot pins 22, the segments 21 being provided at their rear ends with apertured lugs 23 which are received between the respective pairs of pivot lugs 20,20 and pivotally connected thereto by the transverse pivot pins 22. As shown in FIG. 2, the segments 21 are formed at their rear ends with outwardly extending flanges 24, the pivot lugs 23 being located at the outer end portions of said flanges and thus defining shoulders 25 engagable with the front rim of the muzzle 12 to limit rearward movement of the collar member 14 on the muzzle substantially to the position thereof shown in FIG. 2, namely, to a position such that the rim of the collar member 14 is substantially flush with the front rim of the muzzle 12.

The flanges 24 are further formed with forwardly extending arcuate skirt segments 26 which cooperate to form a substantially annular forwardly facing channel to receive the rear end of a coiled spring 27 which surrounds the segments 21 and which bears at its forward end on annular outwardly extending seat portion 28 formed on the rear end of a camming sleeve member 29 surrounding the segments 21.

The segments 21 are provided with thickened forward portions 30 having rearwardly facing inclined surfaces 31 which are cammingly engagable by the front rim of sleeve member 29. The segments 21 are preferably formed of relatively resilient material, such as spring steel, or the like, allowing some outward flexure of the thickened portions 30 relative to the rearward portions of the segments 21 in a manner presently to be described.

Each segment 21 is provided at the forward end of its thickened portion 30 with a pair of pivot lugs 32,32, for example, opposed pairs of angle brackets secured on flattened recessed portions 33 formed on the forward end portions of the thickened segment elements 30, and pivotally connected between the upstanding flanges of said angle brackets are respective trigger arms 34 which extend rearwardly and which have outwardly projecting lug elements 35 engagable with the forward rim of sleeve member 29 in the manner shown in FIG. 2 to at times hold said sleeve member in its retracted position wherein spring 27 is compressed. The trigger arms 34 are formed with rearwardly facing inclined cam edges 36 which are engagable by the rear shoulders 37 defined by the recesses 33, as is clearly shown in FIG. 2. Thus, the expansive effect produced by firing a first shot from the shotgun will urge the thickened portions 30 outwardly and cause the shoulders 37 to rotate the trigger arms 34 outwardly to disengage lugs 35 from the front rim of sleeve member 29 and thus release said sleeve member so that it can move forwardly by the expansion of the coil spring 27, as will be presently described.

Each segment 21 is formed at one longitudinal edge with a longitudinally extending V-shaped groove 38 and is formed at its opposite longitudinal edge with a longitudinally extending V-shaped rib 39, the ribs 39 interfitting with the grooves 38 in the manner shown in FIG. 3 to provide a sealing action. However, sufficient clearance is provided between the ribs 39 and the grooves 38 to permit enough relative movement of the segments to provide proper action thereof.

In operation, the attachment is mounted on the shotgun barrel 12 in the manner shown in the drawings and described above, and prior to the first shot, the sleeve member 29 is pushed rearwardly to compress the spring 27, and the trigger arms 34 are moved inwardly adjacent the thickened segment portions 30 so that their lugs 35 are engagable with the front rim of the sleeve member 29 to hold the sleeve member in its retracted position, as shown in FIG. 2. When the first shot is fired, the expansive force thereof urges the thickened portions 30 outwardly, causing the shoulders 37 to push the edges 36 outwardly and thereby cause the trigger arms 34 to be rotated outwardly, releasing the sleeve member 29. The expansion of the spring 27 causes the sleeve member 29 to move forwardly whereby its front rim cammingly engages the surfaces 31 and causes the portions 30 of the segments to be rotated inwardly to closing positions wherein the ribs 39 are substantially snugly received in the grooves 38. In this position of the segments, the inside bore defined by the inwardly rotated portions of the segments 21 substantially defines an extension of the inside bore of the shotgun barrel 12, providing the desired choke action for subsequent shots.

As shown in FIG. 2, the inside bore defined by the rear end portions of the segments 21 is slightly greater than the bore of the shotgun barrel 12, being of the order of one thirty-second of an inch larger in diameter than the shotgun bore. However, the inside bore defined by the thickened portions 30 when the sleeve member 29 is released, as above described, is substantially the same as the inside diameter of the barrel 12 of the shotgun.

Thus it will be seen that with the attachment in its cocked position, shown in FIG. 2, the first shot will have more spread than the subsequent shots, but the first shot releases the sleeve 29 to cause the thickened portions 30 to be contracted so as to define a forward extension of the shotgun barrel 12 of substantial length, which will have the effect of concentrating the subsequent shots, whereby to provide a high degree of accuracy of directional effect for such subsequent shots. This provides an increase in gunshot range, without manual adjustment, by extending the length of the shotgun barrel automatically on firing the first round at the intended target. The first round automatically activates the choke device and forces the thickened portions 30 into full choke position, clamped by the sleeve 29, ready for the second shot at the target.

While the specific embodiment above described employs pivotal connections 22 for the choke segments, it will readily be apparent that within the spirit of the invention, any suitable connections may be employed for the segments, as long as the connections are of a nature to permit the required inward and outward movement of the thickened segment portions 30.

FIGS. 5, 6 and 7 clearly illustrate the positions of the parts after the first shotgun blast. Thus, with spring 27 expanded, the sleeve 29 acts cammingly on the inclined annular surfaces 31, as above described, and then slides onto the cylindrical main outer surface portions of thickened elements 30, the trigger arms 34 being restricted in their outward movement by the stop action provided by the generally rectangular forward pivot end portions 41 whose inner corners engage the flat surfaces 33 to thereby limit outward rotation of the trigger arms 34 to positions similar to those shown in FIGS. 5 and 6. This also limits the forward movement of the sleeve member 29 produced by the expansion of the spring 27 by the wedging coaction between the sleeve member and the released trigger arms 34.

It will be further seen from FIG. 7 that the pivot lugs for the respective segments 21 may comprise double lugs 23,23 interleaved with mating pivot lugs 20 provided on the collar member 14, with the pivot pins 22 extending through the interleaved pivot lugs.

While a specific embodiment of an improved choke attachment for a shotgun barrel has been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

Claims

What is claimed is:

1. An automatic choke attachment for a gun comprising, a support collar, means to secure said collar on the muzzle end of a gun barrel, a plurality of barrel extension segments movably secured to said collar and extending longitudinally and forwardly therefrom, said segments being at times movable inwardly and being formed to define an extension of the associated gun barrel, a camming sleeve surrounding the segments and mounted to move longitudinally along said extension segments, rearwardly facing inclined camming surfaces on the extension segments engageable by said sleeve to urge the segments inwardly responsive to forward movement of the camming sleeve, said extension segments being provided at their rear ends with abutment means, a coil spring surrounding the extension segments and engaged between the rear end of the camming sleeve and said abutment means to bias said camming sleeve forwardly, trigger arms pivoted to the segments and being engageable with the forward end of the camming sleeve to hold the camming sleeve retracted against the coil spring, and release means for said trigger arms responsive to a first shot fired through the segments by the gun, said release means including shoulder means on the segments engageable with said trigger arms to urge the trigger arms outwardly responsive to the inside expansive force exerted on the segments by said first shot.

2. The automatic choke attachment of claim 1, and wherein the trigger arms are provided with inclined inner cam edges engaged by said shoulder means.

3. The automatic choke attachment of claim 2, and wherein the barrel extension segments are pivotally connected at their rear ends to the forward end portions of said supporting collar.

4. The automatic choke attachment of claim 3, and wherein the barrel extension segments have interfitting longitudinal ribs and grooves at their longitudinal edges to provide a sealing action.

5. The automatic choke attachment of claim 3, and wherein the barrel extension segments are each provided with an apertured lug and said collar is provided with spaced pairs of apertured pivot lugs, said lugs of the segments being received between said pairs of pivot lugs with their apertures in alignment, and pins extend through the aligned apertures to form the pivotal connection of the barrel segments to the collar.

6. The automatic choke attachment of claim 1, wherein said collar is provided with a notch in its rear edge to slidably receive a gun sight fixed to the muzzle end of a gun barrel.

7. The automatic choke attachment of claim 1, wherein each of said barrel extension segments is provided at its forward end with a thickened portion, there being a pair of opposed spaced angle brackets secured on a flattened recessed outer surface at the forward end of each thickened portion, the forward end of each trigger arm being pivotally connected between one of said pairs of angle brackets.