US2968111A - Adjustable gun choke - Google Patents

Description

' Jan. 17, 1961 H.-W. STEANE 2,968,111

ADJUSTABLE GUN CHOKE Filed June 13, 1958 2 Sheets-Sheet 1 J n. 17, 19 t H. w. STEANE 2,968,111

ADJUSTABLE GUN CHOKE Filed June 15, 1958 '2 Sheet s-Shet 2 INVENI" OR ATTORNEY S United States Patent O ADJUSTABLE GUN CHOKE Herbert Welles Steane, West Hartford, Conn., assignor to The Poly Choke Company, Incorporated, East Hartford, Conn., a corporation of Connecticut Filed June 13, 1958, Ser. No. 741,769

3 Claims. (Cl. 42--79) This invention relates to choking mechanism for firearms such as shotguns or the like, and more particularly to an adjustable choke which may be adjusted to give various degrees of constriction of the muzzle end of the gun bar-rel such, for example, as shown in United States Letters Patent No. 2,102,931, dated December 21, 1937, to Ezekiel Field White. The present application is a continuation in part of my application, Serial No. 463,572, filed October 20, 1954, which has now become abandoned. More particularly, it is contemplated by the present invention to provide a choking mechanism giving improved results as compared with prior mechanisms of this character in that a more uniform arrangement of the shot mass will be obtained with the result that an improved shot pattern is effected upon the target.

Tests of the present mechanism have shown that the average pattern of shot obtained by the present mechanism at various settings of the choke is closer than that previously obtained at the same setting with prior chokes and also a more consistent and uniform result is effected with respect, for example, to the percentages of shot which are received in a thirty inch circle on the target at a distance of forty yards.

Generally the present mechanism comprises a shell or element secured to the muzzle end of the gun barrel, this shell being longitudinally slotted through its forward end so as to be divided into segments between the slots, which segments may be bent or displaced inwardly about their junction with the body of the shell so as to constrict the muzzle and produce a choking effect. This inward bending or displacement of the shell segments is obtained by the longitudinal movement of a sleeve upon the shell, the sleeve having means to cam the fingers or segments inwardly adjacent their free ends.

Previously adjustable chokes have been made having a rotatable adjusting sleeve which, when rotated through a complete revolution, produced about seven standard positions called (1) full open, (2) No. 1 position, (3) improved cylinder, (4) No. 3 position, (5) Modified cylinder, (6) No. 5 position and (7) full choke. As ind'cia is placed on the mechanism to indicate the position at which it is set, it will be seen that the complete range of adjustment must be obtained during one complete revolution of the adjusting sleeve. Therefore, as this sleeve is threaded to the main body or shell of the choke and is drawn rearwardly over this body by rotation upon these threads, the pitch of the threads is so chosen as to give a predetermined longitudinal movement of the sleeve. As the choking is produced by the inward displazement of segments or fingers of the shell by cooperating cam or inclined portions arranged on the inner surface of the shell and the outer surface of the segments, the angle of these inclined surfaces must be properly correlated to the pitch of the threads as will be explained hereinafter.

In prior mechanisms of this kind the pitch of the thread was relatively high, and as a result some difficulty was encountered in securing proper results both as to a uni- "ice form shot pattern and as to an average close pattern upon the target. For example, in some instances the choke mechanism has been reamed when set at full open position which means that it would have full bore diam eter at this position. This was found to produce an overchoked effect, however, when the sleeve was drawn rearwardly to full choke position with the result that either a cross fire would be produced or possibly a blown up pattern due to the fact that the gases of the discharge blew up behind the pellets and destroyed the effectiveness of the choke.

To remedy this condition the choke in some instances was reamed at improved cylinder position or the third position referred to above. The result of this was that the full open and No. 1 positions of the sleeve had very little effect or control on the shot pattern, and hence the use of some of the positions of adjustment was lost;

One object of the present invention is to provide a new and improved choking mechanism for shotguns, such that the choke may be reamed in full open position without effecting an overchoked condition when the mechanism is in full choke position whereby the full range of positions of the controlling sleeve may be effectively employed.

A still further object of the invention is to produce animproved choking mechanism for shotguns or the like whereby an improved average shot pattern will be obtained for the various positions to which the mechanism may be adjusted and whereby there may also be obtained a more uniform shot pattern at any position to which the mechanism is adjusted.

A still further object of the invention is to produce a choking mechanism wherein a controlling sleeve is mounted upon an element or shell, the latter having flexible segments to effect a choking action, the sleeve being threadedly mounted upon the shell, and the shell and sleeve having cooperating inclined camming surfaces whereby longitudinal movement of the sleeve will effect the bending or displacement of the fingers or segments of the shell and wherein the pitch of the threads upon the sleeve and the angles of the inclined cooperating camming surfaces upon the sleeve and shell will be so related to each other that a more efiicient and more uniform control of the shot pattern will be effected.

To these and other ends the invention consists in the novel features and combinations of parts to be hereinafter described and claimed.

In the accompanying drawings:

Fig. l is a view partly in section of a gun choke embodying my invention, the choking mechanism being shown in open position;

Fig. 2 is an enlarged view, partly in section, of the shell or element of the choke;

Fig. 3 is an enlarged view, partly in section, of the adjusting sleeve; and

Fig. 4 is a fragmentary sectional view of the choking mechanism, showing the sleeve in a rearward position upon the shell such as occupied when the mechanism is adjusted to full choke position.

To illustrate a preferred embodiment of my invention I have shown in the drawings a gun barrel 10 having its outer end portion somewhat reduced and threaded as shown at 11 to receive a shell 12 having internal threads 13 at its rear end to be received upon the threads 11 of the barrel so that the shell projects forwardly from the barrel. The shell 12 is provided with a plurality of slots 14 disposed longitudinally thereof and opening through the forward end of the shell so as to provide a plurality of segments 15 between the slots. These segments, as will be explained hereinafter, are of such a character that they may be bent or displaced inwardly about their connection with the rearward portion or body of the shell,

with which they are, of course, integral, to constrict the muzzle of the gun and provide a choking action.

The segments 15 of the shell are provided with inclined shoulders 16 adjacent their intermediate portions, these shoulders or inclined surfaces being arranged in an annular series about the shell, this surface sloping toward the forward end of the shell. Similarly the segments 15 are provided adjacent their forward ends with a second annular surface of inclined forwardly sloping surfaces 17. As may be noted from Fig. 2, for example, the angle of inclination of the shoulders 16 is approximately five degrees with respect to the axis of the barrel while the inclined surfaces 17 at the forward ends of the segments have a considerably steeper angle such, for example, as an angle of 13 degrees and thirty minutes. These angles are so arranged, as will be explained hereinafter, that when the segments are bent or displaced inwardly due to longitudinal movement of the adjusting sleeve, the segments will be backed up by cooperating surfaces on the adjusting sleeve over a considerable area.

The shell 12 is provided with external threads 20 at a position rearwardly of the rear ends of the slots 14, and a sleeve 21 having internal threads 22 is mounted upon the threads 20 of the shell so that adjustment of the sleeve will effect longitudinal movement thereof relatively to the shell.

Also, as shown more particularly in Fig. 3, the sleeve is provided with an annular inclined inner surface 23 adjacent its intermediate portion and with a second annular inclined surface 24 adjacent its forward end.

As will be seen from Figs. 1 and 4, the inclined surface 23 is adapted to engage the inclined surface 16 upon the shell or element when the sleeve is moved rearwardly upon the element and cam the fingers or segments 15 of the shell inwardly to a choking position. Similarly the in clined surface 24 upon the sleeve is adapted to engage the surfaces 17 upon the segments 15 to assist in the inward camming action and also together with the inclined surface 23 to firmly support the segments against outward displacement particularly upon discharge of the gun.

It may also be noted from Fig. 3 that the angle of the inclined surface 23 with respect to the axis of the gun barrel is slightly greater than that of the surfaces 16 in that it is six degrees while the angle of the inclined surface 24 is fourteen degrees and thirty minutes or about one degree more than that of the inclined surfaces 17 with which the surface 24 cooperates. With this relation between the angles of the inclined surfaces on the sleeve and element, it will be seen that in the full choke position shown in Fig. 4, the inclined surfaces 16 and 17 of the segments are supported or backed up substantially throughout their entire lengths by the inclined surfaces upon the sleeve. This is highly desirable for as the segments present a constricted bore section relatively to that of the muzzle of the barrel 10, the charge of shot will tend to force them outwardly. At the full open position of the gun shown in Fig. l, we do not have such firm support of the segments by the inclined surfaces of the sleeve, but in this position such support is not so necessary as there is not such great pressure upon the segments in the full open position of the choke mechanism. It will also be apparent that, while in full open position of the parts the angles of the inclined surfaces of the sleeve are respectively one degree greater than those of the cooperating inclined surfaces upon the segments, when the latter have been displaced or bent inwardly, as shown in Fig. 4, the angles upon the inclined surfaces of the two members will be substantially the same as those of the segments will have been increased relatively to the axis of the gun due to their having been displaced or bent inwardly at their forward ends.

The angles of the inclined surfaces of the element and sleeve are smaller than those employed in prior choking mechanisms of this character so that there will be less choking action obtained. Moreover, the pitch of the cooperating threads 20 and 22 upon the element and sleeve 4 is twenty four to the inch as compared with a thread pitch of sixteen to the inch employed upon the corresponding elements on prior choke mechanisms of this character for a twelve gauge gun.

Thus the longitudinal movement of the sleeve upon the shell in one revolution of the sleeve upon the shell is less than that in prior constructions and, as the camming angles of the inclined surfaces upon the sleeve and shell are less than previously employed, less choking action will be obtained for a full turn of the sleeve than in prior constructions. For example, in the present mechanism a choking action of from .019 to .021 inch will be obtained for a full turn of the adjusting sleeve as compared with a choking action of .036 inch in previous constructions.

It has been determined, however, that even with this smaller choking action, closer patterns will be obtained with the present mechanism than has been the case in the past. For example, at full choke an average pattern shows that approximately 76.5 percent of the pellets were received in a thirty inch circle upon the target at a distance of forty yards from the gun as compared with a 70 percent pattern obtained previously. Similarly a modified choke position gives an average pattern of 67.5 percent as against a previous average of approximately 60 percent.

Also with the present choke a better control of the pellets is obtained as the tests show more uniform results as to percentages of shot which will be received within a thirtyinch circle upon the target, showing less variation from one discharge of the gun to another. Therefore, in the present structure the pitch of the cooperating threads upon the sleeve and shell is so related to the inclined camming surfaces upon these two members that, while the amount of restriction of the gun muzzle is not as great as that previously obtained, the result is greatly improved.

As shown in Fig. 1 of the drawings, the gun barrel 10 is provided with a shoulder 26 against which seats a cooperating shoulder 27 at the rear end of the element or shell 12, the threads 11 being provided upon a reduced portion of the barrel. The engagement of the shoulders 26 and 27 positions the choke upon the barrel by limiting the threaded engagement of these two parts. It will also be noted that the bore of the choke element at the rear of the slots 14 is flared outwardly, as shown at 28 (Figs. 1 and 2), from a point adjacent the rear edges of the slots to a point 29 marking the extreme forward end of the reduced portion of the barrel. This flaring shape or forwardly tapering shape of the bore of the choke element 12 provides a regathering chamber for the shot of the charge which greatly improves the choke patterns produced by the gun. The charge has an opportunity to expand slightly when leaving the barrel of the gun but will be gradually regathered by the gradually tapering surface 28 to be constricted by the choke element according to the degree of choke for which the sleeve 21 is adjusted. This gradually flaring surface gives better results than if an abrupt shoulder were provided on the element at the point 29.

Moreover, as the choke is reamed at full open position, all of the various positions of the sleeve are usable for various desired shot patterns, and no overchoking results at full choke position to effect a cross fire or blown up shot pattern. The improved mechanism produces a rhythmic or harmonic flow of shot to provide a stabilized pattern at all positions of adjustment between a full open position and a full choke position, which latter position does not produce the deleterious effects due to overchoking.

While I have shown and described a preferred embodiment of my invention, it will be understood that it is not to be limited to all of the details shown, but is capable of modification and variation within the spirit of the invention and within the scope of the claims.

What I claim is:

1. An adjustable choke for gun barrels comprising a tubular cylindrical element adapted to be secured at its rear end to the muzzle end of a gun barrel, said element having slots opening through its forward end to divide its forward portion into spaced segments displaceable inwardly, said segments having at least a first and a second annular series of tapering shoulders thereon, one of said series being spaced from the other longitudinally of the axis of the element and being inclined rearwardly, a sleeve embracing said element and threadedly connected thereto for movement longitudinally thereof, said sleeve having complementary tapering interior annular shoulders therein to engage the shoulders of the segments and displace the latter inwardly to constrict the efiective size of the opening therebetween, the beveled surfaces of the outer series of shoulders on the segments being inclined at an angle of 13 degrees and 30 minutes with respect to the axis of the barrel, those of the second series making an angle of 5 degrees with the axis of the barrel, and the angle of the shoulders on the sleeve being greater respectively than those of the cooperating shoulder in the element, and the pitch of the threads on the sleeve and element being substantially twenty-four to the inch.

2. An adjustable choke for gun barrels comprising a tubular cylindrical element adapted to be secured at its rear end to the muzzle end of a gun barrel, said element having slots opening through its forward end to divide its forward portion into spaced segments displaceable inwardly, said segments having at least a first and a second annular series of tapering shoulders thereon, one of said series being spaced from the other longitudinally of the axis of the element and being inclined rearwardly, a sleeve embracing said element and threadedly connected thereto for movement longitudinally thereof, said sleeve having complementary tapering interior annular shoulders therein to engage the shoulders of the segments and displace the latter inwardly to constrict the eifective size of the opening therebetween, the beveled surface of the first series of shoulders on the segments being inclined at an angle of 13 degrees: and 30 minutes with respect to the axis of the barrel, and those of the second series at an angle of 5 degrees with respect to the axis of the barrel, the angle of the shoulders on the sleeve being greater respectively than those of the cooperating shoulders on the segments, the element being reamed at its full open position to substantially the diameter of the given barrel bore, and the pitch of the threads on the sleeve and element being such as to effect a restriction of the barrel bore at full choke position of from .019 to .021 inch upon a full turn of the sleeve.

3. An adjustable choke for gun barrels as in claim 2 wherein the portion of said tubular cylindrical element rearwardly of said slots has a continuous wall, and the bore of said portion is flared outwardly from a point adjacent the rear ends of said slots to a point adjacent the end of the gun barrel to provide a regathering chamber for the shot of the charge larger than the bore at its rear end adjacent the muzzle end of the barrel and tapering inwardly toward the slotted portion of the element.

References Cited in the file of this patent UNITED STATES PATENTS 85,949 McKenzie Jan. 19, 1869 1,773,260 Cutts Aug. 19, 1930 2,102,931 White Dec. 21, 1937 2,335,138 White Nov. 23, 1943 2,476,438 Wright July 19, 1949 2,656,638 Cobb Oct. 27, 1953

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